js-apis-distributed-data.md

# Distributed Data Management

>![](../../public_sys-resources/icon-note.gif) **NOTE**<br/>
>The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.


## Modules to Import

```
import distributedData from '@ohos.data.distributedData';
```


## distributedData.createKVManager

createKVManager(config: KVManagerConfig, callback: AsyncCallback&lt;KVManager&gt;): void

Creates a **KVManager** object to manage key-value (KV) stores. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name| Type| Mandatory| Description|
| ----- | ------ | ------ | ------ |
| config | [KVManagerConfig](#kvmanagerconfig) | Yes | Configuration of the **KVManager** object, including the bundle name and user information of the caller.|
| callback | AsyncCallback&lt;[KVManager](#kvmanager)&gt; | Yes | Callback invoked to return the **KVManager** object created.|

**Example**
```
let kvManager;
try {
    const kvManagerConfig = {
        bundleName : 'com.example.datamanagertest',
        userInfo : {
            userId : '0',
            userType : distributedData.UserType.SAME_USER_ID
        }
    }
    distributedData.createKVManager(kvManagerConfig, function (err, manager) {
        if (err) {
            console.log("createKVManager err: "  + JSON.stringify(err));
            return;
        }
        console.log("createKVManager success");
        kvManager = manager;
    });
} catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```

## distributedData.createKVManager

createKVManager(config: KVManagerConfig): Promise&lt;KVManager&gt;

Creates a **KVManager** object to manage KV stores. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name| Type| Mandatory| Description|
| ----- | ------ | ------ | ------ |
| config |[KVManagerConfig](#kvmanager) | Yes | Configuration of the **KVManager** object, including the bundle name and user information of the caller.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;[KVManager](#kvmanager)&gt; | Promise used to return the **KVManager** object created.|

**Example**

```
let kvManager;
try {
    const kvManagerConfig = {
        bundleName : 'com.example.datamanagertest',
        userInfo : {
            userId : '0',
            userType : distributedData.UserType.SAME_USER_ID
        }
    }
    distributedData.createKVManager(kvManagerConfig).then((manager) => {
        console.log("createKVManager success");
        kvManager = manager;
    }).catch((err) => {
        console.log("createKVManager err: "  + JSON.stringify(err));
    });
} catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```

## KVManagerConfig

Provides configuration of the **KVManager** object, including the bundle name and user information of the caller.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name| Type| Mandatory| Description|
| ----- | ------ | ------ | ------ |
| userInfo | [UserInfo](#userinfo) | Yes | User information.|
| bundleName | string | Yes | Bundle name.|

## UserInfo

Defines user information.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name| Type| Mandatory| Description|
| ----- | ------ | ------ | ------ |
| userId | string | Yes | User ID.|
| userType | [UserType](#usertype) | Yes | User type.|


## UserType

Defines the user type.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name| Default Value| Description|
| ----- | ------ | ------ |
| SAME_USER_ID | 0 | User who logs in to different devices using the same account.|


## KVManager

Creates a **KVManager** object to obtain KV store information. Before calling any method in **KVManager**, you must use **createKVManager** to create a **KVManager** object.

### getKVStore

getKVStore&lt;T extends KVStore&gt;(storeId: string, options: Options, callback: AsyncCallback&lt;T&gt;): void

Creates and obtains a KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name| Type| Mandatory| Description|
| ----- | ------ | ------ | ------ |
| storeId | string | Yes | Unique identifier of the KV store. The length cannot exceed [MAX_STORE_ID_LENGTH](#constants).|
| options | [Options](#options) | Yes | Configuration of the KV store.|
| callback | AsyncCallback&lt;T&gt;, &lt;T extends KVStore&gt;| Yes | Callback invoked to return the KV store created.|

**Example**

```
let kvStore;
let kvManager;
try {
    const options = {
        createIfMissing : true,
        encrypt : false,
        backup : false,
        autoSync : true,
        kvStoreType : distributedData.KVStoreType.SINGLE_VERSION,
        securityLevel : distributedData.SecurityLevel.S2,
    };
    kvManager.getKVStore('storeId', options, function (err, store) {
        if (err) {
            console.log("getKVStore err: "  + JSON.stringify(err));
            return;
        }
        console.log("getKVStore success");
        kvStore = store;
    });
} catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```


### getKVStore

getKVStore&lt;T extends KVStore&gt;(storeId: string, options: Options): Promise&lt;T&gt;

Creates and obtains a KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name  | Type               | Mandatory | Description   |
| ------- | ---------------------- | ---- | -------------------- |
| storeId  | string      | Yes  | Unique identifier of the KV store. The length cannot exceed [MAX_STORE_ID_LENGTH](#constants).|
| options  | [Options](#options)   | Yes  | Configuration of the KV store.|


**Return value**

| Type                                   | Description       |
| -------------------------------------- | ------------------------ |
| Promise&lt;T&gt; &lt;T extends KVStore&gt; | Promise used to return the KV store created.|

**Example**

```
let kvStore;
let kvManager;
try {
    const options = {
        createIfMissing : true,
        encrypt : false,
        backup : false,
        autoSync : true,
        kvStoreType : distributedData.KVStoreType.SINGLE_VERSION,
        securityLevel : distributedData.SecurityLevel.S2,
    };
    kvManager.getKVStore('storeId', options).then((store) => {
        console.log("getKVStore success");
        kvStore = store;
    }).catch((err) => {
        console.log("getKVStore err: "  + JSON.stringify(err));
    });
} catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```

### closeKVStore<sup>8+</sup> ###

closeKVStore(appId: string, storeId: string, kvStore: KVStore, callback: AsyncCallback&lt;void&gt;): void

Closes a KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**


| Name  | Type             | Mandatory| Description        |
| ------- | -----------------   | ---- | --------------------------- |
| appId    | string              | Yes  | Bundle name of the app that invokes the KV store.        |
| storeId  | string  | Yes  | Unique identifier of the KV store to close. The length cannot exceed the value of [MAX_STORE_ID_LENGTH](#constants).|
| kvStore  | [KVStore](#kvstore) | Yes  | KV store to close.     |
| callback | AsyncCallback&lt;void&gt; | Yes  | Callback used to return the result. If the KV store is closed, **true** will be returned. Otherwise, **false** will be returned.  |

**Example**

```
let kvStore;
let kvManager;
const options = {
    createIfMissing : true,
    encrypt : false,
    backup : false,
    autoSync : true,
    kvStoreType : distributedData.KVStoreType.SINGLE_VERSION,
    schema : '',
    securityLevel : distributedData.SecurityLevel.S2,
 }
 try {
    kvManager.getKVStore('storeId', options, async function (err, store) {
    console.log('getKVStore success');
    kvStore = store;
    await kvManager.closeKVStore('appId', 'storeId', kvStore, function (err, data) {
        console.log('closeKVStore success');
    });
    });
} catch (e) {
    console.log('closeKVStore e ' + e);
}
```


### closeKVStore<sup>8+</sup> ###

closeKVStore(appId: string, storeId: string, kvStore: KVStore): Promise&lt;void&gt;

Closes a KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description       |
| -----  | ------  | ---- | ----------------------------- |
| appId  | string  | Yes  | Bundle name of the app that invokes the KV store.           |
| storeId | string | Yes  | Unique identifier of the KV store to close. The length cannot exceed the value of [MAX_STORE_ID_LENGTH](#constants).|
| kvStore | [KVStore](#kvstore)  | Yes  | KV store to close.       |

**Return value**

| Type         | Description           |
| ------------- | -------------- |
| Promise<void> | Promise used to return the result. If the KV store is closed, **true** will be returned. Otherwise, **false** will be returned.|

**Example**

```
let kvManager;
let kvStore;
const options = {
    createIfMissing : true,
    encrypt : false,
    backup : false,
    autoSync : true,
    kvStoreType : distributedData.KVStoreType.SINGLE_VERSION,
    schema : '',
    securityLevel : distributedData.SecurityLevel.S2,
}
 try {
    kvManager.getKVStore('storeId', options).then(async (store) => {
    console.log('getKVStore success');
    kvStore = store;
    await kvManager.closeKVStore('appId', 'storeId', kvStore).then(() => {
        console.log('closeKVStore success');
    }).catch((err) => {
        console.log('closeKVStore err ' + JSON.stringify(err));
    });
    }).catch((err) => {
        console.log('CloseKVStore getKVStore err ' + JSON.stringify(err));
    });
 } catch (e) {
    console.log('closeKVStore e ' + e);
}  
```


### deleteKVStore<sup>8+</sup> ###

deleteKVStore(appId: string, storeId: string, callback: AsyncCallback&lt;void&gt;): void

Deletes a KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| appId  | string  | Yes  | Bundle name of the app that invokes the KV store.    |
| storeId | string | Yes  | Unique identifier of the KV store to delete. The length cannot exceed the value of [MAX_STORE_ID_LENGTH](#constants).|
| callback | AsyncCallback&lt;void&gt;  | Yes  | Callback used to return the result. If the KV store is deleted, **true** will be returned. Otherwise, **false** will be returned.  |

**Example**

```
let kvManager;
let kvStore;
const options = {
    createIfMissing : true,
    encrypt : false,
    backup : false,
    autoSync : true,
    kvStoreType : distributedData.KVStoreType.SINGLE_VERSION,
    schema : '',
    securityLevel : distributedData.SecurityLevel.S2,
}
try {
    kvManager.getKVStore('store', options, async function (err, store) {
        console.log('getKVStore success');
        kvStore = store;
        await kvManager.deleteKVStore('appId', 'storeId', function (err, data) {
            console.log('deleteKVStore success');
        });
    });
} catch (e) {
    console.log('DeleteKVStore e ' + e);
}
```

### deleteKVStore<sup>8+</sup> ###

deleteKVStore(appId: string, storeId: string): Promise&lt;void&gt;

Deletes a KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| appId  | string  | Yes  | Bundle name of the app that invokes the KV store.    |
| storeId | string | Yes  | Unique identifier of the KV store to delete. The length cannot exceed the value of [MAX_STORE_ID_LENGTH](#constants).|


**Return value**

| Type         | Description           |
| ------------- | -------------- |
| Promise&lt;void&gt; | Promise used to return the result. If the KV store is deleted, **true** will be returned. Otherwise, **false** will be returned.|

**Example**

```
let kvManager;
let kvStore;
const options = {
    createIfMissing : true,
    encrypt : false,
    backup : false,
    autoSync : true,
    kvStoreType : distributedData.KVStoreType.SINGLE_VERSION,
    schema : '',
    securityLevel : distributedData.SecurityLevel.S2,
}
try {
    kvManager.getKVStore('storId', options).then(async (store) => {
        console.log('getKVStore success');
        kvStore = store;
        await kvManager.deleteKVStore('appId', 'storeId').then(() => {
            console.log('deleteKVStore success');
        }).catch((err) => {
            console.log('deleteKVStore err ' + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log('getKVStore err ' + JSON.stringify(err));
    });
} catch (e) {
    console.log('deleteKVStore e ' + e);
}
```


### getAllKVStoreId<sup>8+</sup> ###

getAllKVStoreId(appId: string, callback: AsyncCallback&lt;string[]&gt;): void

Obtains the IDs of all the KV stores that are created using **getKvStore** and have not been deleted using **deleteKvStore**. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| appId  | string  | Yes   | Bundle name of the app that invokes the KV store.    |
| callback | AsyncCallback&lt;void&gt; | Yes  |Callback used to return the KV store IDs obtained. |

**Example**

```
let kvManager;
try {
    kvManager.getAllKVStoreId('appId', function (err, data) {
        console.log('GetAllKVStoreId success');
        console.log('GetAllKVStoreId size = ' + data.length);
    });
} catch (e) {
    console.log('GetAllKVStoreId e ' + e);
}
```


### getAllKVStoreId<sup>8+</sup> ###

getAllKVStoreId(appId: string): Promise&lt;string[]&gt;

Obtains the IDs of all the KV stores that are created using **getKvStore** and have not been deleted using **deleteKvStore**. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| appId  | string  | Yes   | Bundle name of the app that invokes the KV store.    |


**Return value**

| Type         | Description           |
| ------------- | -------------- |
| Promise&lt;string[]&gt;| Promise used to return the KV store IDs obtained.|

**Example**

```
let kvManager;
try {
    console.log('GetAllKVStoreId');
    kvManager.getAllKVStoreId('apppId').then((data) => {
        console.log('getAllKVStoreId success');
        console.log('size = ' + data.length);
    }).catch((err) => {
        console.log('getAllKVStoreId err ' + JSON.stringify(err));
    });
} catch(e) {
    console.log('getAllKVStoreId e ' + e);
}
```


### on<sup>8+</sup> ###

on(event: 'distributedDataServiceDie', deathCallback: Callback&lt;void&gt;): void

Subscribes to the **distributedDataServiceDie** events. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| event  | 'distributedDataServiceDie'  | Yes   | Type of events to subscribe to.     |
| deathCallback  | Callback&lt;void&gt;  | Yes   | Callback invoked when the distributed data service is dead.   |

**Example**

```
let kvManager;
try {
    
    console.log('KVManagerOn');
    const deathCallback = function () {
        console.log('death callback call');
    }
    kvManager.on('distributedDataServiceDie', deathCallback);
} catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```


### off<sup>8+</sup> ###

off(event: 'distributedDataServiceDie', deathCallback?: Callback&lt;void&gt;): void

Unsubscribes from the **distributedDataServiceDie** events. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| event  | 'distributedDataServiceDie'  | Yes   | Type of events to unsubscribe from.     |
| deathCallback  | Callback&lt;void&gt;  | No   | Callback used to return the **distributedDataServiceDie** events.   |


**Example**

```
let kvManager;
try {
    console.log('KVManagerOff');
    const deathCallback = function () {
        console.log('death callback call');
    }
    kvManager.off('distributedDataServiceDie', deathCallback);
} catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
    
```

## Options

Provides KV store configuration.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| createIfMissing  | boolean | No| Whether to create a KV store if no database file exists. By default, a KV store is created.    |
| encrypt  | boolean | No|Whether to encrypt database files. By default, database files are not encrypted.    |
| backup  | boolean | No|Whether to back up database files. By default, database files are backed up.     |
| autoSync  | boolean | No|Whether to automatically synchronize database files. By default, database files are not automatically synchronized.    |
| kvStoreType | [KVStoreType](#kvstoretype) | No|Type of the KV store to create. By default, a device KV store is created. The device KV store stores data for multiple devices that collaborate with each other.|
| securityLevel | [SecurityLevel](#securitylevel) | No|Security level of the KV store. By default, the security level is not set. |
| schema<sup>8+</sup> | [Schema](#schema8) | No| Schema used to define the values stored in a KV store.|


## KVStoreType

Defines the KV store types.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Default Value| Description                   |
| ---   | ----  | ----------------------- |
| DEVICE_COLLABORATION  | 0 | Device KV store.  |
| SINGLE_VERSION  | 1 | Single KV store. |
| MULTI_VERSION   | 2 | Multi-version KV store. This type is not supported currently. |


## SecurityLevel

Defines the KV store security levels.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Default Value| Description                   |
| ---   | ----  | ----------------------- |
| NO_LEVEL  | 0 | No security level is set for the KV store.  |
| S0  | 1 | The KV store security level is public. |
| S1  | 2 | The KV store security level is low. If data leakage occurs, minor impact will be caused on the database. |
| S2  | 3 | The KV store security level is medium. If data leakage occurs, moderate impact will be caused on the database. |
| S3  | 5 | The KV store security level is high. If data leakage occurs, major impact will be caused on the database. |
| S4  | 6 | The KV store security level is critical. If data leakage occurs, severe impact will be caused on the database. |


## Constants

Defines the KV store constants.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Default Value| Description                   |
| ---   | ----  | ----------------------- |
| MAX_KEY_LENGTH  | 1024 | Maximum length (in bytes) of a key in the KV store.  |
| MAX_VALUE_LENGTH  | 4194303 | Maximum length (in bytes) of a value in the KV store. |
| MAX_KEY_LENGTH_DEVICE  | 896 | Maximum length of the device coordinate key. |
| MAX_STORE_ID_LENGTH  | 128 | Maximum length (in bytes) of a KV store ID. |
| MAX_QUERY_LENGTH  | 512000 | Maximum query length. |
| MAX_BATCH_SIZE  | 128 | Maximum size of a batch operation. |

## Schema<sup>8+</sup> ##

Defines a database schema. When creating or opening a KV store, you can create a **Schema** object and put it into **Options**.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

| Name | Type| Description                   |
| ---   | ----  | ----------------------- |
| root<sup>8+</sup>  | [FieldNode](#fieldnode8) | JSON root object. |
| indexes<sup>8+</sup>  | Array\<string> | String array in JSON format. |
| mode<sup>8+</sup>  | number | Schema mode. |
| skip<sup>8+</sup>  | number |  Size of a skip of the schema. |

### constructor<sup>8+</sup> ###

constructor()

A constructor used to create a **Schema** instance.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

## FieldNode<sup>8+</sup> ##

Represents a **Schema** instance, which provides the methods for defining the values stored in a KV store.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

| Name | Type| Description                   |
| ---   | ----  | ----------------------- |
| nullable<sup>8+</sup>  | boolean | Whether the database field can be null.  |
| default<sup>8+</sup>  | string | Default value of a **FieldNode**.|
| type<sup>8+</sup>  | number | Value to store.|

### constructor<sup>8+</sup> ###

constructor(name: string)

A constructor used to create a **FieldNode** instance with a string field.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name| Type| Mandatory| Description           |
| ------ | -------- | ---- | --------------- |
| name   | string   | Yes  | Value of **FieldNode**.|

### appendChild<sup>8+</sup> ###

appendChild(child: FieldNode): boolean

Appends a child node to this **FieldNode**.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| child  | [FieldNode](#fieldnode8) | Yes   | Child node to append.  |


**Return value**

| Type         | Description           |
| ------------- | -------------- |
| boolean |Returns **true** if the operation is successful; returns **false** otherwise.|

**Example**

```
import ddm from '@ohos.data.distributedData';
try {
    let node = new ddm.FieldNode("root");
    let child1 = new ddm.FieldNode("child1");
    let child2 = new ddm.FieldNode("child2");
    let child3 = new ddm.FieldNode("child3");
    node.appendChild(child1);
    node.appendChild(child2);
    node.appendChild(child3);
    console.log("appendNode " + node.toJson());
    child1 = null;
    child2 = null;
    child3 = null;
    node = null;
} catch (e) {
    console.log("AppendChild " + e);
}
```


## KvStoreResultSet<sup>8+</sup> ##

Provides methods to obtain the KV store result set and query or move the data read position. Before calling any method in **KvStoreResultSet**, you must use **KvStore** to create a **KvStore** instance.


### getCount<sup>8+</sup> ###

getCount(): number

Obtains the number of rows in the result set.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type  | Description              |
| ------ | --------------    |
| number |Number of rows obtained.         |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const count = resultSet.getCount();
    console.log("GetCount " + count);
} catch (e) {
    console.log("GetCount fail " + e);
}
```

### getPosition<sup>8+</sup> ###

getPosition(): number

Obtains the current data read position (position from which data is read) in the result set.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type  | Description              |
| ------ | --------------    |
| number |Current data read position obtained.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const position = resultSet.getPosition();
    console.log("getPosition " + position);
} catch (e) {
    console.log("GetPosition fail " + e);
}
```


### moveToFirst<sup>8+</sup> ###

moveToFirst(): boolean

Moves the data read position to the first row.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the operation is successful; returns **false** otherwise.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.moveToFirst();
    console.log("moveToFirst " + moved);
} catch (e) {
    console.log("MoveToFirst fail " + e);
}
```


### moveToLast<sup>8+</sup> ###

moveToLast(): boolean

Moves the data read position to the last row.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the operation is successful; returns **false** otherwise.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.moveToLast();
    console.log("moveToLast " + moved);
} catch (e) {
    console.log("moveToLast fail " + e);
}
```


### moveToNext<sup>8+</sup> ###

moveToNext(): boolean

Moves the data read position to the next row.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the operation is successful; returns **false** otherwise.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.moveToNext();
    console.log("moveToNext " + moved);
} catch (e) {
    console.log("moveToNext fail " + e);
}
```


### moveToPrevious<sup>8+</sup> ###

moveToPrevious(): boolean

Moves the data read position to the previous row.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the operation is successful; returns **false** otherwise.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.moveToPrevious();
    console.log("moveToPrevious " + moved);
} catch (e) {
    console.log("moveToPrevious fail " + e);
}
```


### move<sup>8+</sup> ###

move(offset: number): boolean

Moves the data read position with the specified offset from the current position.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| offset  | number  | Yes   | Offset to move the data read position. A negative value means to move backward, and a positive value means to move forward.  |

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the operation is successful; returns **false** otherwise.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.move();
    console.log("move " + moved);
} catch (e) {
    console.log("move fail " + e);
}
```


### moveToPosition<sup>8+</sup> ###

moveToPosition(position: number): boolean

Moves the data read position from 0 to an absolute position.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| position  | number  | Yes   |Absolute position to move to.         |

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the operation is successful; returns **false** otherwise.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.moveToPosition();
    console.log("moveToPosition " + moved);
} catch (e) {
    console.log("moveToPosition fail " + e);
}
```


### isFirst<sup>8+</sup> ###

isFirst(): boolean

Checks whether the data read position is the first row.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the data read position is the first row; returns **false** otherwise.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.isFirst();
    console.log("isFirst " + moved);
} catch (e) {
    console.log("isFirst fail " + e);
}
```


### isLast<sup>8+</sup> ###

isLast(): boolean

Checks whether the data read position is the last row.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the data read position is the last row; returns **false** otherwise.  |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.isLast();
    console.log("isLast " + moved);
} catch (e) {
    console.log("isLast fail " + e);
}
```

### isBeforeFirst<sup>8+</sup> ###

isBeforeFirst(): boolean

Checks whether the data read position is before the first row.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the read position is before the first row; returns **false** otherwise. |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.isBeforeFirst();
    console.log("isBeforeFirst " + moved);
} catch (e) {
    console.log("isBeforeFirst fail " + e);
}
```


### isAfterLast<sup>8+</sup> ###

isAfterLast(): boolean

Checks whether the data read position is after the last row.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description              |
| ------  | --------------    |
| boolean |Returns **true** if the data read position is after the last row; returns **false** otherwise. |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.isAfterLast();
    console.log("isAfterLast " + moved);
} catch (e) {
    console.log("isAfterLast fail " + e);
}
```


### getEntry<sup>8+</sup> ###

getEntry(): Entry

Obtains a KV pair.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| Entry   |KV pair obtained.|

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + err);
    });
    const moved = resultSet.moveToNext();
    const entry  = resultSet.getEntry();
    console.log("getEntry " + JSON.stringify(entry));
} catch (e) {
    console.log("getEntry fail " + e);
}
```


## Query<sup>8+</sup> ##

Provides methods to create a **Query** object, which defines different data query criteria.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

### constructor<sup>8+</sup> ###

constructor() 

A constructor used to create a **Schema** instance.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core


### reset<sup>8+</sup> ###

reset(): Query

Resets the **Query** object that contains common query options.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core


**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object reset.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.equalTo("key", "value");
    console.log("query is " + query.getSqlLike());
    query.reset();
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("simply calls should be ok :" + e);
}
```


### equalTo<sup>8+</sup> ###

equalTo(field: string, value: number|string|boolean): Query;

Creates a **Query** object to match the specified field whose value is equal to the specified value.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| value  | number/string/boolean  | Yes   | Value specified.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.equalTo("field", "value");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### notEqualTo<sup>8+</sup> ###

notEqualTo(field: string, value: number|string|boolean): Query

Creates a **Query** object to match the specified field whose value is not equal to the specified value.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| value  | number/string/boolean  | Yes   | Value specified.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.notEqualTo("field", "value");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### greaterThan<sup>8+</sup> ###

greaterThan(field: string, value: number|string|boolean): Query

Creates a **Query** object to match the specified field whose value is greater than the specified value.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| value  | number\|string\|boolean  | Yes   | Value specified.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.greaterThan("field", "value");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### lessThan<sup>8+</sup> ###

lessThan(field: string, value: number|string): Query

Creates a **Query** object to match the specified field whose value is less than the specified value.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| value  | number\|string\|boolean  | Yes   | Value specified.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.lessThan("field", "value");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### greaterThanOrEqualTo<sup>8+</sup> ###

greaterThanOrEqualTo(field: string, value: number|string): Query

Creates a **Query** object to match the specified field whose value is greater than or equal to the specified value.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| value  | number\|string\|boolean  | Yes   | Value specified.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.greaterThanOrEqualTo("field", "value");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### lessThanOrEqualTo<sup>8+</sup> ###

lessThanOrEqualTo(field: string, value: number|string): Query

Creates a **Query** object to match the specified field whose value is less than or equal to the specified value.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| value  | number\|string\|boolean  | Yes   | Value specified.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.lessThanOrEqualTo("field", "value");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### isNull<sup>8+</sup> ###

isNull(field: string): Query

Creates a **Query** object to match the specified field whose value is **null**.


**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.isNull("field");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### inNumber<sup>8+</sup> ###

inNumber(field: string, valueList: number[]): Query

Creates a **Query** object to match the specified field whose value is within the specified list of numbers.


**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| valueList  | number[]  | Yes   | List of numbers.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.inNumber("field", [0, 1]);
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### inString<sup>8+</sup> ###

inString(field: string, valueList: string[]): Query

Creates a **Query** object to match the specified field whose value is within the specified list of strings.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| valueList  | string[]  | Yes   | List of strings.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.inString("field", ['test1', 'test2']);
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### notInNumber<sup>8+</sup> ###

notInNumber(field: string, valueList: number[]): Query

Creates a **Query** object to match the specified field whose value is not within the specified list of numbers.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| valueList  | number[]  | Yes   | List of numbers.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.notInNumber("field", [0, 1]);
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### notInString<sup>8+</sup> ###

notInString(field: string, valueList: string[]): Query

Creates a **Query** object to match the specified field whose value is not within the specified list of strings.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| valueList  | string[]  | Yes   | List of strings.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.notInString("field", ['test1', 'test2']);
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### like<sup>8+</sup> ###

like(field: string, value: string): Query

Creates a **Query** object to match the specified field whose value is similar to the specified string.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| valueList  | string  | Yes   | String specified.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.like("field", "value");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### unlike<sup>8+</sup> ###

unlike(field: string, value: string): Query

Creates a **Query** object to match the specified field whose value is not similar to the specified string.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |
| valueList  | string  | Yes   | String specified.|

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.unlike("field", "value");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### and<sup>8+</sup> ###

and(): Query

Creates a **Query** object with the AND condition.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.notEqualTo("field", "value1");
    query.and();
    query.notEqualTo("field", "value2");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### or<sup>8+</sup> ###

or(): Query

Creates a **Query** object with the OR condition.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.notEqualTo("field", "value1");
    query.or();
    query.notEqualTo("field", "value2");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### orderByAsc<sup>8+</sup> ###

orderByAsc(field: string): Query

Creates a **Query** object to sort the query results in ascending order.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.notEqualTo("field", "value");
    query.orderByAsc("field");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### orderByDesc<sup>8+</sup> ###

orderByDesc(field: string): Query

Creates a **Query** object to sort the query results in descending order.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field to match. It must start with $ and cannot contain ^. |

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.notEqualTo("field", "value");
    query.orderByDesc("field");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### limit<sup>8+</sup> ###

limit(total: number, offset: number): Query

Creates a **Query** object to specify the number of results and where to start.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| total  | number  | Yes   |Number of results to query. |
| offset | number  | Yes   |Start position for query. |

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.notEqualTo("field", "value");
    query.limit("total", "offset");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### isNotNull<sup>8+</sup> ###

isNotNull(field: string): Query

Creates a **Query** object with a specified field that is not null.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| fieId  | string  | Yes   |Field specified.     |

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.isNotNull("field");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### beginGroup<sup>8+</sup> ###

beginGroup(): Query

Creates a **Query** object for a query condition group with a left parenthesis.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.beginGroup();
    query.isNotNull("field");
    query.endGroup();
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### endGroup<sup>8+</sup> ###

endGroup(): Query

Creates a **Query** object for a query condition group with a right parenthesis.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.beginGroup();
    query.isNotNull("field");
    query.endGroup();
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### prefixKey<sup>8+</sup> ###

prefixKey(prefix: string): Query

Creates a **Query** object with a specified key prefix.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| prefix | string  | Yes   |Key prefix.    |

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.prefixKey("$.name");
    query.prefixKey("0");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
    console.log("dumplicated calls should be ok :" + e);
}
```


### setSuggestIndex<sup>8+</sup> ###

setSuggestIndex(index: string): Query

Creates a **Query** object with an index preferentially used for query.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| index  | string  | Yes   |Index preferentially used for query.  |

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.setSuggestIndex("$.name");
    query.setSuggestIndex("0");
    console.log("query is " + query.getSqlLike());
    query = null;
} catch (e) {
   console.log("dumplicated calls should be ok :" + e);
}
```


### deviceId<sup>8+</sup> ###

deviceId(deviceId:string):Query

Creates a **Query** object with the device ID as the key prefix.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| deviceId | string  | Yes   |Device ID.  |


**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    query.deviceId("deviceId");
    console.log("query is " + query.getSqlLike());
} catch (e) {
    console.log("should be ok on Method Chaining : " + e);
}
```


### getSqlLike<sup>8+</sup> ###

getSqlLike():string

Obtains the query statement of this **Query** object.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| [Query](#query8) |**Query** object Created.|

**Example**

```
try {
    let query = new distributedData.Query();
    let sql1 = query.getSqlLike();
    console.log("GetSqlLike sql=" + sql1);
} catch (e) {
    console.log("dumplicated calls should be ok : " + e);
}
```


## KVStore

Provides methods to manage data in a KV store, for example, adding or deleting data and subscribing to data changes or completion of data synchronization. Before calling any method in **KVStore**, you must use **getKVStore** to obtain a **KVStore** object.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

### put

put(key: string, value: Uint8Array | string | number | boolean, callback: AsyncCallback&lt;void&gt;): void

Adds a KV pair of the specified type to this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| key    | string  | Yes   |Key of the KV pair to add. It cannot be empty, and the length cannot exceed [MAX_KEY_LENGTH](#constants).  |
| value  | Uint8Array \| string \| number \| boolean | Yes   |Value of the KV pair to add. The value type can be Uint8Array, number, string, or boolean. A value of the Uint8Array or string type cannot exceed [MAX_VALUE_LENGTH](#constants).  |
| callback | AsyncCallback&lt;void&gt; | Yes   |Callback invoked to return the result.  |

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value-test-string';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT, function (err,data) {
        if (err != undefined) {
            console.log("put err: " + JSON.stringify(err));
            return;
        }
        console.log("put success");
    });
}catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```


### put

put(key: string, value: Uint8Array | string | number | boolean): Promise&lt;void&gt;

Adds a KV pair of the specified type to this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| key    | string  | Yes   |Key of the KV pair to add. It cannot be empty, and the length cannot exceed [MAX_KEY_LENGTH](#constants).  |
| value  | Uint8Array \| string \| number \| boolean | Yes   |Value of the KV pair to add. The value type can be Uint8Array, number, string, or boolean. A value of the Uint8Array or string type cannot exceed [MAX_VALUE_LENGTH](#constants).  |

**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value-test-string';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT).then((data) => {
        console.log("put success: " + JSON.stringify(data));
    }).catch((err) => {
        console.log("put err: " + JSON.stringify(err));
    });
}catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```


### delete

delete(key: string, callback: AsyncCallback&lt;void&gt;): void

Deletes a KV pair from this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| key    | string  | Yes   |Key of the KV pair to delete. It cannot be empty, and the length cannot exceed [MAX_KEY_LENGTH](#constants).  |
| callback  | AsyncCallback&lt;void&gt;  | Yes   |Callback invoked to return the result.  |

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value-test-string';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT, function (err,data) {
        if (err != undefined) {
            console.log("put err: " + JSON.stringify(err));
            return;
        }
        console.log("put success");
        kvStore.delete(KEY_TEST_STRING_ELEMENT, function (err,data) {
            if (err != undefined) {
                console.log("delete err: " + JSON.stringify(err));
                return;
            }
            console.log("delete success");
        });
    });
}catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```


### delete

delete(key: string): Promise&lt;void&gt;

Deletes a KV pair from this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| key    | string  | Yes   |Key of the KV pair to delete. It cannot be empty, and the length cannot exceed [MAX_KEY_LENGTH](#constants).  |

**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value-test-string';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT).then((data) => {
        console.log("put success: " + JSON.stringify(data));
        kvStore.delete(KEY_TEST_STRING_ELEMENT).then((data) => {
            console.log("delete success");
        }).catch((err) => {
            console.log("delete err: " + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log("put err: " + JSON.stringify(err));
    });
}catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```


### on

on(event: 'dataChange', type: SubscribeType, observer: Callback&lt;ChangeNotification&gt;): void

Subscribes to data changes of the specified type. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| event  |'dataChange'  | Yes   |Type of the events.       |
| type  |[SubscribeType](#subscribetype) | Yes   |Type of data changes.    |
| observer |Callback&lt;[ChangeNotification](#changenotification)&gt; | Yes   |Callback invoked to return the result.|

**Example**

```
let kvStore;
kvStore.on('dataChange', distributedData.SubscribeType.SUBSCRIBE_TYPE_LOCAL, function (data) {
    console.log("dataChange callback call data: " + JSON.stringify(data));
});
```


### on

on(event: 'syncComplete', syncCallback: Callback&lt;Array&lt;[string, number]&gt;&gt;): void

Subscribes to data synchronization completion events. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| event  |'syncComplete' | Yes   |Type of the events.       |
| syncCallback  |Callback&lt;Array&lt;[string, number]&gt;&gt; | Yes   |Callback invoked to return the result.    |

**Example**

```
let kvStore;
kvStore.on('syncComplete', function (data) {
    console.log("syncComplete callback call data: " + data);
});
```

### off<sup>8+</sup>

off(event:'dataChange', observer?: Callback&lt;ChangeNotification&gt;): void

Unsubscribes from data change events. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| event  |'dataChange'  | Yes   |Type of the events.       |
| observer |Callback&lt;[ChangeNotification](#changenotification)&gt; |No   |Callback used to return the result.|

**Example**

```
let kvStore;
kvStore.on('dataChange', function (data) {
    console.log("syncComplete callback call data: " + data);
});
kvStore.off('dataChange', function (data) {
    console.log("syncComplete callback call data: " + data);
});
```


### putBatch<sup>8+</sup>

putBatch(entries: Entry[], callback: AsyncCallback&lt;void&gt;): void

Inserts KV pairs in batches to this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| entries  |[Entry](#entry)[] | Yes   |KV pairs to insert in batches. |
| callback |Asyncallback&lt;void&gt; |Yes    |Callback invoked to return the result.|

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries, async function (err,data) {
        console.log('putBatch success');
        await kvStore.getEntries('batch_test_string_key', function (err,entrys) {
            console.log('getEntries success');
            console.log('entrys.length: ' + entrys.length);
            console.log('entrys[0]: ' + JSON.stringify(entrys[0]));
        });
    });
}catch(e) {
    console.log('PutBatch e ' + e);
}
```


### putBatch<sup>8+</sup>

putBatch(entries: Entry[]): Promise&lt;void&gt;

Inserts KV pairs in batches to this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| entries  |[Entry](#entry)[] | Yes   |KV pairs to insert in batches. |

**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
        await kvStore.getEntries('batch_test_string_key').then((entrys) => {
            console.log('getEntries success');
            console.log('PutBatch ' + JSON.stringify(entries));
        }).catch((err) => {
            console.log('getEntries fail ' + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('PutBatch e ' + e);
}
```


### deleteBatch<sup>8+</sup>

deleteBatch(keys: string[], callback: AsyncCallback&lt;void&gt;): void

Deletes KV pairs in batches from this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| keys  |string[] | Yes   |KV pairs to delete in batches. |
| callback  |AsyncCallback&lt;void&gt; | Yes   |Callback invoked to return the result. |

**Example**

```
let kvStore;
try {
    let entries = [];
    let keys = [];
    for (var i = 0; i < 5; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
        keys.push(key + i);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries, async function (err,data) {
        console.log('putBatch success');
        await kvStore.deleteBatch(keys, async function (err,data) {
            console.log('deleteBatch success');
        });
    });
}catch(e) {
    console.log('DeleteBatch e ' + e);
}
```


### deleteBatch<sup>8+</sup> ###

deleteBatch(keys: string[]): Promise&lt;void&gt;

Deletes KV pairs in batches from this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| keys   |string[] | Yes   |KV pairs to delete in batches. |

**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    let entries = [];
    let keys = [];
    for (var i = 0; i < 5; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
        keys.push(key + i);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
        await kvStore.deleteBatch(keys).then((err) => {
            console.log('deleteBatch success');
        }).catch((err) => {
            console.log('deleteBatch fail ' + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('DeleteBatch e ' + e);
}
```


### startTransaction<sup>8+</sup> ###

startTransaction(callback: AsyncCallback&lt;void&gt;): void

Starts the transaction in this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| callback  |AsyncCallback&lt;void&gt; | Yes   |Callback invoked to return the result. |

**Example**

```
let kvStore;
function putBatchString(len, prefix) {
    let entries = [];
    for (var i = 0; i < len; i++) {
        var entry = {
            key : prefix + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    return entries;
}
try {
    var count = 0;
    kvStore.on('dataChange', 0, function (data) {
        console.log('startTransaction 0' + data)
        count++;
    });
    kvStore.startTransaction(async function (err,data) {
        console.log('startTransaction success');
        let entries = putBatchString(10, 'batch_test_string_key');
        console.log('entries: ' + JSON.stringify(entries));
        await kvStore.putBatch(entries, async function (err,data) {
            console.log('putBatch success');
        });
    });
}catch(e) {
    console.log('startTransaction e ' + e);
}
```


### startTransaction<sup>8+</sup> ###

startTransaction(): Promise&lt;void&gt;

Starts the transaction in this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    var count = 0;
    kvStore.on('dataChange', distributedData.SubscribeType.SUBSCRIBE_TYPE_ALL, function (data) {
        console.log('startTransaction ' + JSON.stringify(data));
        count++;
    });
    kvStore.startTransaction().then(async (err) => {
        console.log('startTransaction success');
    }).catch((err) => {
        console.log('startTransaction fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('startTransaction e ' + e);
}
```


### commit<sup>8+</sup> ###

commit(callback: AsyncCallback&lt;void&gt;): void

Commits the transaction in this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| callback  |AsyncCallback&lt;void&gt; | Yes   |Callback invoked to return the result. |

**Example**

```
let kvStore;
try {
    kvStore.commit(function (err,data) {
        if (err == undefined) {
            console.log('commit success');
        } else {
            console.log('commit fail');
        }
    });
}catch(e) {
    console.log('Commit e ' + e);
}
```


### commit<sup>8+</sup> ###

commit(): Promise&lt;void&gt;

Commits the transaction in this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    kvStore.commit().then(async (err) => {
        console.log('commit success');
    }).catch((err) => {
        console.log('commit fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('Commit e ' + e);
}
```


### rollback<sup>8+</sup> ###

rollback(callback: AsyncCallback&lt;void&gt;): void

Rolls back the transaction in this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| callback  |AsyncCallback&lt;void&gt; | Yes   |Callback invoked to return the result. |

**Example**

```
let kvStore;
try {
    kvStore.rollback(function (err,data) {
        if (err == undefined) {
            console.log('commit success');
        } else {
            console.log('commit fail');
        }
    });
}catch(e) {
    console.log('Rollback e ' + e);
}
```


### rollback<sup>8+</sup> ###

rollback(): Promise&lt;void&gt;

Rolls back the transaction in this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    kvStore.rollback().then(async (err) => {
        console.log('rollback success');
    }).catch((err) => {
        console.log('rollback fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('Rollback e ' + e);
}
```


### enableSync<sup>8+</sup> ###

enableSync(enabled: boolean, callback: AsyncCallback&lt;void&gt;): void

Sets data synchronization, which can be enabled or disable. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| enabled  |boolean | Yes   |Whether to enable data synchronization. The value **true** means to enable data synchronization, and **false** means the opposite. |
| callback  |AsyncCallback&lt;void&gt; | Yes   |Callback invoked to return the result. |

**Example**

```
let kvStore;
try {
    kvStore.enableSync(true, function (err,data) {
        if (err == undefined) {
            console.log('enableSync success');
        } else {
            console.log('enableSync fail');
        }
    });
}catch(e) {
    console.log('EnableSync e ' + e);
}
```


### enableSync<sup>8+</sup> ###

enableSync(enabled: boolean): Promise&lt;void&gt;

Enables or disables data synchronization. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| enabled  |boolean | Yes   |Whether to enable data synchronization. The value **true** means to enable data synchronization, and **false** means the opposite. |

**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    kvStore.enableSync(true).then((err) => {
        console.log('enableSync success');
    }).catch((err) => {
        console.log('enableSync fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('EnableSync e ' + e);
}
```


### setSyncRange<sup>8+</sup> ###

setSyncRange(localLabels: string[], remoteSupportLabels: string[], callback: AsyncCallback&lt;void&gt;): void

Sets the data synchronization range. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| localLabels  |string[] | Yes   |Synchronization labels set for the local device. |
| remoteSupportLabels  |string[] | Yes   |Synchronization labels set for remote devices. |
| callback  |AsyncCallback&lt;void&gt; | Yes   |Callback invoked to return the result. |

**Example**

```
let kvStore;
try {
    const localLabels = ['A', 'B'];
    const remoteSupportLabels = ['C', 'D'];
    kvStore.setSyncRange(localLabels, remoteSupportLabels, function (err,data) {
        console.log('SetSyncRange put success');
    });
}catch(e) {
    console.log('SetSyncRange e ' + e);
}
```


### setSyncRange<sup>8+</sup> ###

setSyncRange(localLabels: string[], remoteSupportLabels: string[]): Promise&lt;void&gt;

Sets the data synchronization range. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| localLabels  |string[] | Yes   |Synchronization labels set for the local device. |
| remoteSupportLabels  |string[] | Yes   |Synchronization labels set for remote devices. |


**Return value**

| Type   | Description      |
| ------  | -------   |
| Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    const localLabels = ['A', 'B'];
    const remoteSupportLabels = ['C', 'D'];
    kvStore.setSyncRange(localLabels, remoteSupportLabels).then((err) => {
        console.log('setSyncRange success');
    }).catch((err) => {
        console.log('delete fail ' + err);
    });
}catch(e) {
    console.log('SetSyncRange e ' + e);
}
```


## SubscribeType

Defines the subscription type.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Default Value  | Description                   |
| -----  | ------   | ----------------------- |
| SUBSCRIBE_TYPE_LOCAL  |0 |Local data changes. |
| SUBSCRIBE_TYPE_REMOTE |1 |Remote data changes. |
| SUBSCRIBE_TYPE_ALL  |2 |Local and remote data changes. |

## ChangeNotification

Defines the content of data change notifications, including inserted data, updated data, deleted data, and device ID.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Type  |Readable  |Writable  | Description                   |
| ----- | -------   | -----| ------|------------------------ |
| insertEntries | [Entry](#entry)[]   | Yes |  Yes|Data inserted.  |
| updateEntries | [Entry](#entry)[]   | Yes |  Yes|Data updated.  |
| deleteEntries | [Entry](#entry)[]   | Yes |  Yes|Data deleted.  |
| deviceId | string   | Yes |  Yes|UUID of the device. |

## Entry

Defines the KV pairs stored in the KV store.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Type  |Readable  |Writable  | Description                   |
| ----- | -------   | -----| ------|------------------------ |
| key | string   | Yes |  Yes|Key of the KV pair stored in the KV store.  |
| value | [Value](#value) | Yes |  Yes|Value of the KV pair stored in the KV store.  |


## Value

Defines the value in a KV pair.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Type  |Readable  |Writable  | Description                   |
| ----- | -------   | -----| ------|------------------------ |
| type | [ValueType](#value)   | Yes |  Yes|Type of the value.  |
| value | Uint8Array / string / number / boolean| Yes |  Yes|Value of the KV pair stored in the KV store.  |

## ValueType

Enumerates the types of values in KV pairs.

These value types can be used only by internal applications.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name | Default Value  | Description                   |
| -----  | ------   | ----------------------- |
| STRING  |0 |String. |
| INTEGER |1 |Integer. |
| FLOAT   |2 |Float (single-precision floating point). |
| BYTE_ARRAY   |3 |Byte array. |
| BOOLEAN   |4 |Boolean. |
| DOUBLE   |5 |Double (double-precision floating point). |

## SingleKVStore

Provides methods to query and synchronize data in a single KV store. This class inherits from **KVStore**. Before calling any method in **SingleKVStore**, you must use **getKVStore** to obtain a **SingleKVStore** object.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

### get

get(key: string, callback: AsyncCallback&lt;Uint8Array | string | boolean | number&gt;): void

Obtains the value of a specified key. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| key    |string   | Yes   |Key of the value to obtain. It cannot be empty, and the length cannot exceed [MAX_KEY_LENGTH](#constants). |
| callback  |AsyncCallback&lt;Uint8Array \| string \| boolean \| number&gt;) | Yes   |Callback used to return the value obtained. |

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value-test-string';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT, function (err,data) {
        if (err != undefined) {
            console.log("put err: " + JSON.stringify(err));
            return;
        }
        console.log("put success");
        kvStore.get(KEY_TEST_STRING_ELEMENT, function (err,data) {
            console.log("get success data: " + data);
        });
    });
}catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```


### get

get(key: string): Promise&lt;Uint8Array | string | boolean | number&gt;

Obtains the value of a specified key. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| key    |string   | Yes   |Key of the value to obtain. It cannot be empty, and the length cannot exceed [MAX_KEY_LENGTH](#constants). |


**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;Uint8Array \| string \| boolean \| number&gt; |Promise used to return the value obtained.|

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value-test-string';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT).then((data) => {
        console.log("put success: " + JSON.stringify(data));
        kvStore.get(KEY_TEST_STRING_ELEMENT).then((data) => {
            console.log("get success data: " + data);
        }).catch((err) => {
            console.log("get err: " + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log("put err: " + JSON.stringify(err));
    });
}catch (e) {
    console.log("An unexpected error occurred. Error:" + e);
}
```

### getEntries<sup>8+</sup> ###

getEntries(keyPrefix: string, callback: AsyncCallback&lt;Entry[]&gt;): void

Obtains the KV pairs that match the specified key prefix. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| keyPrefix    |string   | Yes   |Key prefix to match. |
| callback    |AsyncCallback&lt;[Entry](#entry)[]&gt;   | Yes   |Callback used to return the KV pairs obtained. |

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_number_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.INTEGER,
                value : 222
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries, async function (err,data) {
        console.log('putBatch success');
        await kvStore.getEntries('batch_test_number_key', function (err,entrys) {
            console.log('getEntries success');
            console.log('entrys.length: ' + entrys.length);
            console.log('entrys[0]: ' + JSON.stringify(entrys[0]));
        });
    });
}catch(e) {
    console.log('PutBatch e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(keyPrefix: string): Promise&lt;Entry[]&gt;

Obtains the KV pairs that match the specified key prefix. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| keyPrefix    |string   | Yes   |Key prefix to match. |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[Entry](#entry)[]&gt; |Promise used to return the KV pairs obtained.|

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + entries);
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
        await kvStore.getEntries('batch_test_string_key').then((entrys) => {
            console.log('getEntries success');
            console.log('entrys.length: ' + entrys.length);
            console.log('entrys[0]: ' + JSON.stringify(entrys[0]));
            console.log('entrys[0].value: ' + JSON.stringify(entrys[0].value));
            console.log('entrys[0].value.value: ' + entrys[0].value.value);
        }).catch((err) => {
            console.log('getEntries fail ' + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('PutBatch e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(query: Query, callback: AsyncCallback&lt;Entry[]&gt;): void

Obtains the KV pairs that match the specified **Query** object. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| query  |[Query](#query8)   | Yes   |**Query** object to match. |
| callback  |AsyncCallback&lt;[Entry](#entry)[]&gt;   | Yes   |Callback used to return the KV pairs obtained. |

**Example**

```
let kvStore;
try {
    var arr = new Uint8Array([21,31]);
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_bool_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.BYTE_ARRAY,
                value : arr
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries, async function (err,data) {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        await kvStore.getEntries(query, function (err,entrys) {
            console.log('getEntries success');
            console.log('entrys.length: ' + entrys.length);
            console.log('entrys[0]: ' + JSON.stringify(entrys[0]));
        });
    });
    console.log('GetEntries success');
}catch(e) {
    console.log('GetEntries e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(query: Query): Promise&lt;Entry[]&gt;

Obtains the KV pairs that match the specified **Query** object. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| query  |[Query](#query8)   | Yes   |**Query** object to match. |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[Entry](#entry)[]&gt; |Promise used to return the KV pairs obtained.|

**Example**

```
try {
    var arr = new Uint8Array([21,31]);
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_bool_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.BYTE_ARRAY,
                value : arr
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        await kvStore.getEntries(query).then((entrys) => {
            console.log('getEntries success');
        }).catch((err) => {
            console.log('getEntries fail ' + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log('GetEntries putBatch fail ' + JSON.stringify(err))
    });
    console.log('GetEntries success');
}catch(e) {
    console.log('GetEntries e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(keyPrefix: string, callback: AsyncCallback&lt;KvStoreResultSet&gt;): void

Obtains the result set with the specified key prefix from this single KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| keyPrefix  |string   | Yes   |Key prefix to match.|
| callback  |AsyncCallback&lt;[KvStoreResultSet](#kvstoreresultset8)&gt;   | Yes   |Callback used to return the result set obtained.|

**Example**

```
let kvStore;
try {
    let resultSet;
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries, async function (err, data) {
        console.log('GetResultSet putBatch success');
        await kvStore.getResultSet('batch_test_string_key', async function (err, result) {
            console.log('GetResultSet getResultSet success');
            resultSet = result;
            kvStore.closeResultSet(resultSet, function (err, data) {
                console.log('GetResultSet closeResultSet success');
            })
        });
    });
}catch(e) {
    console.log('GetResultSet e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(keyPrefix: string): Promise&lt;KvStoreResultSet&gt;

Obtains the result set with the specified key prefix from this single KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------  | ----  | ----------------------- |
| keyPrefix  |string   | Yes   |Key prefix to match.|

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[KvStoreResultSet](#kvstoreresultset8)&gt; |Promise used to return the result set obtained.|

**Example**

```
let kvStore;
try {
    let resultSet;
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
    }).catch((err) => {
        console.log('PutBatch putBatch fail ' + JSON.stringify(err));
    });
    kvStore.getResultSet('batch_test_string_key').then((result) => {
        console.log('GetResult getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + JSON.stringify(err));
    });
    kvStore.closeResultSet(resultSet).then((err) => {
        console.log('GetResult closeResultSet success');
    }).catch((err) => {
        console.log('closeResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('GetResult e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(query: Query, callback: AsyncCallback&lt;KvStoreResultSet&gt;): void

Obtains the **KvStoreResultSet** object that matches the specified **Query** object. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query  |Query    | Yes   |**Query** object to match.            |
| callback  |AsyncCallback&lt;[KvStoreResultSet](#kvstoreresultset8)&gt;   | Yes   |Callback used to return the **KvStoreResultSet** object obtained.|

**Example**

```
let kvStore;
try {
    let resultSet;
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries, async function (err, data) {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        await kvStore.getResultSet(query, async function (err, result) {
            console.log('getResultSet success');
            resultSet = result;
        });
    });
} catch(e) {
    console.log('GetResultSet e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(query: Query): Promise&lt;KvStoreResultSet&gt;

Obtains the **KvStoreResultSet** object that matches the specified **Query** object. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query  |[Query](#query8)    | Yes   |**Query** object to match.            |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[KvStoreResultSet](#kvstoreresultset8)&gt; |Promise used to return the **KvStoreResultSet** object obtained.|

**Example**

```
let kvStore;
try {
    let resultSet;
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
    const query = new distributedData.Query();
    query.prefixKey("batch_test");
    kvStore.getResultSet(query).then((result) => {
        console.log(' getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('GetResultSet e ' + e);
}
```

### closeResultSet<sup>8+</sup> ###

closeResultSet(resultSet: KvStoreResultSet, callback: AsyncCallback&lt;void&gt;): void

Closes the **KvStoreResultSet** object obtained by **getResultSet**. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| resultSet  |[KvStoreResultSet](#kvstoreresultset8)   | Yes   |**KvStoreResultSet** object to close.            |
| callback  |AsyncCallback&lt;void&gt;   | Yes   |Callback used to return the execution result.            |

**Example**

```
let kvStore;
try {
    let resultSet = null;
    kvStore.closeResultSet(resultSet, function (err, data) {
        if (err == undefined) {
            console.log('closeResultSet success');
        } else {
            console.log('closeResultSet fail');
        }
    });
}catch(e) {
    console.log('CloseResultSet e ' + e);
}
```


### closeResultSet<sup>8+</sup> ###

closeResultSet(resultSet: KvStoreResultSet): Promise&lt;void&gt;

Closes the **KvStoreResultSet** object obtained by **getResultSet**. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| resultSet  |[KvStoreResultSet](#kvstoreresultset8)   | Yes   |**KvStoreResultSet** object to close.            |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    let resultSet = null;
    kvStore.closeResultSet(resultSet).then(() => {
        console.log('closeResultSet success');
    }).catch((err) => {
        console.log('closeResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('CloseResultSet e ' + e);
}
```


### getResultSize<sup>8+</sup> ###

getResultSize(query: Query, callback: AsyncCallback&lt;number&gt;): void

Obtains the number of results that matches the specified **Query** object. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query  |[Query](#query8)   | Yes   |**Query** object to match.        |
| callback  |AsyncCallback&lt;number&gt;   | Yes   |Callback used to return the number of results obtained.        |

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries, async function (err, data) {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        await kvStore.getResultSize(query, async function (err, resultSize) {
            console.log('getResultSet success');
        });
    });
} catch(e) {
    console.log('GetResultSize e ' + e);
}
```


### getResultSize<sup>8+</sup> ###

getResultSize(query: Query): Promise&lt;number&gt;

Obtains the number of results that matches the specified **Query** object. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query  |[Query](#query8)   | Yes   |**Query** object to match.        |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;number&gt; |Promise used to return the number of results obtained.|

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
    const query = new distributedData.Query();
    query.prefixKey("batch_test");
    kvStore.getResultSize(query).then((resultSize) => {
        console.log('getResultSet success');
    }).catch((err) => {
        console.log('getResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('GetResultSize e ' + e);
}
```


### removeDeviceData<sup>8+</sup> ###

removeDeviceData(deviceId: string, callback: AsyncCallback&lt;void&gt;): void

Deletes data of a device. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string   | Yes   |ID of the target device.      |
| callback  |AsyncCallback&lt;void&gt;   | Yes   |Callback used to return the result.     |

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string_2';
const VALUE_TEST_STRING_ELEMENT = 'value-string-002';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT, async function (err,data) {
        console.log('put success');
        const deviceid = 'no_exist_device_id';
        await kvStore.removeDeviceData(deviceid, async function (err,data) {
            if (err == undefined) {
                console.log('removeDeviceData success');
            } else {
                console.log('removeDeviceData fail');
                await kvStore.get(KEY_TEST_STRING_ELEMENT, async function (err,data) {
                    console.log('RemoveDeviceData get success');
                });
            }
        });
    });
}catch(e) {
    console.log('RemoveDeviceData e ' + e);
}
```


### removeDeviceData<sup>8+</sup> ###

removeDeviceData(deviceId: string): Promise&lt;void&gt;

Deletes data of a device. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string   | Yes   |ID of the target device.      |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string_2';
const VALUE_TEST_STRING_ELEMENT = 'value-string-001';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT).then((err) => {
        console.log('removeDeviceData put success');
    }).catch((err) => {
        console.log('put fail ' + JSON.stringify(err));
    });
    const deviceid = 'no_exist_device_id';
    kvStore.removeDeviceData(deviceid).then((err) => {
        console.log('removeDeviceData success');
    }).catch((err) => {
        console.log('removeDeviceData fail ' + JSON.stringify(err));
    });
    kvStore.get(KEY_TEST_STRING_ELEMENT).then((data) => {
        console.log('get success data:' + data);
    }).catch((err) => {
        console.log('RemoveDeviceData get fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('RemoveDeviceData e ' + e);
}
```


### on<sup>8+</sup> ###

on(event: 'syncComplete', syncCallback: Callback&lt;Array&lt;[string, number]&gt;&gt;): void

Subscribes to the synchronization completion events. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| event  |'syncComplete'   | Yes   |Event triggered when the synchronization is complete.   |
| syncCallback  |Callback&lt;Array&lt;[string, number]&gt;&gt;   | Yes   |Callback used to return the synchronization result.   |

**Example**

```
let kvStore;
const KEY_TEST_FLOAT_ELEMENT = 'key_test_float';
const VALUE_TEST_FLOAT_ELEMENT = 321.12;
try {
    kvStore.on('syncComplete', function (data) {
        console.log('syncComplete ' + data)
    });
    kvStore.put(KEY_TEST_FLOAT_ELEMENT, VALUE_TEST_FLOAT_ELEMENT).then((data) => {
        console.log('syncComplete put success');
    }).catch((error) => {
        console.log('syncComplete put fail ' + error);
    });
}catch(e) {
    console.log('syncComplete put e ' + e);
}
```


### off<sup>8+</sup> ###

off(event: 'syncComplete', syncCallback?: Callback&lt;Array&lt;[string, number]&gt;&gt;): void

Unsubscribes from the synchronization completion events. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| event  |'syncComplete'   | Yes   |Event triggered when the synchronization is complete.   |
| syncCallback  |Callback&lt;Array&lt;[string, number]&gt;&gt;   | No   |Callback used to return the synchronization result.   |

**Example**

```
let kvStore;
try {
    const func = function (data) {
        console.log('syncComplete ' + data)
    };
    kvStore.on('syncComplete', func);
    kvStore.off('syncComplete', func);
}catch(e) {
    console.log('syncComplete e ' + e);
}
```


### sync

sync(deviceIdList: string[], mode: SyncMode, allowedDelayMs?: number): void

Manually triggers KV store synchronization synchronously.
**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceIdList  |string[]  | Yes   |IDs of the devices to be synchronized. These devices must be in the same networking environment.   |
| mode  |[SyncMode](#syncmode)   | Yes  |Data synchronization mode.   |
| allowedDelayMs  |number   | No  |Allowed synchronization delay time, in ms.  |

**Example**

```
let kvStore;
kvStore.sync('deviceIds', distributedData.SyncMode.PULL_ONLY, 1000);
```

### setSyncParam<sup>8+</sup> ###

setSyncParam(defaultAllowedDelayMs: number, callback: AsyncCallback&lt;void&gt;): void

Sets the default delay of database synchronization. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| defaultAllowedDelayMs  |number  | Yes   |Default delay allowed for database synchronization, in ms.   |
| callback  |AsyncCallback&lt;void&gt;  | Yes  |Callback used to return the result.  |

**Example**

```
let kvStore;
try {
    const defaultAllowedDelayMs = 500;
    kvStore.setSyncParam(defaultAllowedDelayMs, function (err,data) {
        console.log('SetSyncParam put success');
    });
}catch(e) {
    console.log('testSingleKvStoreSetSyncParam e ' + e);
}
```


### setSyncParam<sup>8+</sup> ###

setSyncParam(defaultAllowedDelayMs: number): Promise&lt;void&gt;

Sets the default delay of database synchronization. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| defaultAllowedDelayMs  |number  | Yes   |Default delay allowed for database synchronization, in ms.   |


**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    const defaultAllowedDelayMs = 500;
    kvStore.setSyncParam(defaultAllowedDelayMs).then((err) => {
        console.log('SetSyncParam put success');
    }).catch((err) => {
        console.log('SetSyncParam put fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('SetSyncParam e ' + e);
}
```


### getSecurityLevel<sup>8+</sup> ###

getSecurityLevel(callback: AsyncCallback&lt;SecurityLevel&gt;): void

Obtains the security level of this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| callback  |AsyncCallback&lt;[SecurityLevel](#securitylevel)&gt;  | Yes   |Callback used to return the security level obtained.   |

**Example**

```
let kvStore;
try {
    kvStore.getSecurityLevel(function (err,data) {
        console.log('getSecurityLevel success');
    });
}catch(e) {
    console.log('GetSecurityLeve e ' + e);
}
```


### getSecurityLevel<sup>8+</sup> ###

getSecurityLevel(): Promise&lt;SecurityLevel&gt;

Obtains the security level of this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[SecurityLevel](#securitylevel)&gt; |Promise used to return the security level obtained.|

**Example**

```
let kvStore;
try {
    kvStore.getSecurityLevel().then((data) => {
        console.log(' getSecurityLevel success');
    }).catch((err) => {
        console.log('getSecurityLevel fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('GetSecurityLeve e ' + e);
}
```


## DeviceKVStore<sup>8+</sup> ##

Provides methods to manage distributed data by device in the distributed system. This class inherits from **KvStore** and provides data query and synchronization methods. Before calling any method in **DeviceKVStore**, you must use **getKVStore** to obtain a **DeviceKVStore** object.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

### get<sup>8+</sup> ###

get(deviceId: string, key: string, callback: AsyncCallback&lt;boolean|string|number|Uint8Array&gt;): void

Obtains the string value that matches the specified key for a device. This method uses an asynchronous callback to return the result.

**System capability**:  SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| key       |string  | Yes   |Key to match.   |
| callback  |AsyncCallback&lt;boolean\|string\|number\|Uint8Array&gt;  | Yes   |Callback used to return the value obtained.   |

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string_2';
const VALUE_TEST_STRING_ELEMENT = 'value-string-002';
try{
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT, async function (err,data) {
        console.log('put success');
        kvStore.get('localDeviceId', KEY_TEST_STRING_ELEMENT, function (err,data) {
            console.log('get success');
        });
    })
}catch(e) {
    console.log('get e' + e);
}
```


### get<sup>8+</sup> ###

get(deviceId: string, key: string): Promise&lt;boolean|string|number|Uint8Array&gt;

Obtains the string value that matches the specified key for a device. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| key       |string  | Yes   |Key to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;boolean/string/number/Uint8Array&gt; |Promise used to return the value obtained.|

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string_2';
const VALUE_TEST_STRING_ELEMENT = 'value-string-002';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT).then(async (data) => {
        console.log(' put success');
        kvStore.get('localDeviceId', KEY_TEST_STRING_ELEMENT).then((data) => {
            console.log('get success');
        }).catch((err) => {
            console.log('get fail ' + JSON.stringify(err));
        });
    }).catch((error) => {
        console.log('put error' + error);
    });
} catch (e) {
    console.log('Get e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(deviceId: string, keyPrefix: string, callback: AsyncCallback&lt;Entry[]&gt;): void

Obtains the KV pairs that match the specified key prefix for a device. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| keyPrefix |string  | Yes   |Key prefix to match.   |
| callback  |AsyncCallback&lt;[Entry](#entry)[]&gt;  | Yes |Callback used to return the KV pairs obtained.   |

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + entries);
    kvStore.putBatch(entries, async function (err,data) {
        console.log('putBatch success');
        await kvStore.getEntries('localDeviceId', 'batch_test_string_key', function (err,entrys) {
            console.log('getEntries success');
            console.log('entrys.length: ' + entrys.length);
            console.log('entrys[0]: ' + JSON.stringify(entrys[0]));
        });
    });
}catch(e) {
    console.log('PutBatch e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(deviceId: string, keyPrefix: string): Promise&lt;Entry[]&gt;

Obtains the KV pairs that match the specified key prefix for a device. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| keyPrefix |string  | Yes   |Key prefix to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[Entry](#entry)[]&gt; |Promise used to return the KV pairs obtained.|

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + entries);
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
        await kvStore.getEntries('localDeviceId', 'batch_test_string_key').then((entrys) => {
            console.log('getEntries success');
            console.log('entrys.length: ' + entrys.length);
            console.log('entrys[0]: ' + JSON.stringify(entrys[0]));
            console.log('entrys[0].value: ' + JSON.stringify(entrys[0].value));
            console.log('entrys[0].value.value: ' + entrys[0].value.value);
        }).catch((err) => {
            console.log('getEntries fail ' + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('PutBatch e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(query: Query, callback: AsyncCallback&lt;Entry[]&gt;): void

Obtains the KV pairs that match the specified **Query** object. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query  |[Query](#query8)  | Yes   |**Query** object to match.   |
| callback |AsyncCallback&lt;[Entry](#entry)[]&gt;  | Yes   |Callback used to return the KV pairs obtained.   |

**Example**

```
let kvStore;
try {
    var arr = new Uint8Array([21,31]);
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_bool_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.BYTE_ARRAY,
                value : arr
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries, async function (err,data) {
        console.log('putBatch success');
        expect(err == undefined).assertTrue();
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        query.deviceId('localDeviceId');
        await kvStore.getEntries(query, function (err,entrys) {
            console.log('getEntries success');
            console.log('entrys.length: ' + entrys.length);
            console.log('entrys[0]: ' + JSON.stringify(entrys[0]));
        });
    });
    console.log('GetEntries success');
}catch(e) {
    console.log('GetEntries e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(query: Query): Promise&lt;Entry[]&gt;

Obtains the KV pairs that match the specified **Query** object. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query  |[Query](#query8)  | Yes   |**Query** object to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[Entry](#entry)[]&gt; |Promise used to return the KV pairs obtained.|

**Example**

```
let kvStore;
try {
    var arr = new Uint8Array([21,31]);
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_bool_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.BYTE_ARRAY,
                value : arr
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        await kvStore.getEntries(query).then((entrys) => {
            console.log('getEntries success');
        }).catch((err) => {
            console.log('getEntries fail ' + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log('GetEntries putBatch fail ' + JSON.stringify(err))
    });
    console.log('GetEntries success');
}catch(e) {
    console.log('GetEntries e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(deviceId: string, query: Query, callback: AsyncCallback&lt;Entry[]&gt;): void

Obtains the KV pairs that match the specified **Query** object for a device. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| query  |[Query](#query8)  | Yes   |**Query** object to match.   |
| callback |AsyncCallback&lt;[Entry](#entry)[]&gt;  | Yes   |Callback used to return the KV pairs obtained.   |

**Example**

```
let kvStore;
try {
    var arr = new Uint8Array([21,31]);
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_bool_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.BYTE_ARRAY,
                value : arr
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries, async function (err,data) {
        console.log('putBatch success');
        expect(err == undefined).assertTrue();
        var query = new distributedData.Query();
        query.deviceId('localDeviceId');
        query.prefixKey("batch_test");
        await kvStore.getEntries('localDeviceId', query, function (err,entrys) {
            console.log('getEntries success');
            console.log('entrys.length: ' + entrys.length);
            console.log('entrys[0]: ' + JSON.stringify(entrys[0]));
        })
    });
    console.log('GetEntries success');
}catch(e) {
    console.log('GetEntries e ' + e);
}
```


### getEntries<sup>8+</sup> ###

getEntries(deviceId: string, query: Query): Promise&lt;Entry[]&gt;

Obtains the KV pairs that match the specified **Query** object for a device. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| query  |[Query](#query8)  | Yes   |**Query** object to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[Entry](#entry)[]&gt; |Promise used to return the KV pairs obtained.|

**Example**

```
let kvStore;
try {
    var arr = new Uint8Array([21,31]);
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_bool_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.BYTE_ARRAY,
                value : arr
            }
        }
        entries.push(entry);
    }
    console.log('entries: ' + JSON.stringify(entries));
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
        var query = new distributedData.Query();
        query.deviceId('localDeviceId');
        query.prefixKey("batch_test");
        await kvStore.getEntries('localDeviceId', query).then((entrys) => {
            console.log('getEntries success');
        }).catch((err) => {
            console.log('getEntries fail ' + JSON.stringify(err));
        });
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
    console.log('GetEntries success');
}catch(e) {
    console.log('GetEntries e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(deviceId: string, keyPrefix: string, callback: AsyncCallback&lt;KvStoreResultSet&gt;): void

Obtains the **KvStoreResultSet** object that matches the specified key prefix for a device. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| keyPrefix |string  | Yes   |Key prefix to match.   |
| callback  |AsyncCallback&lt;[KvStoreResultSet](#kvstoreresultset8)[]&gt;  | Yes |Callback used to return the **KvStoreResultSet** object obtained.   |

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('localDeviceId', 'batch_test_string_key', async function (err, result) {
        console.log('getResultSet success');
        resultSet = result;
        await kvStore.closeResultSet(resultSet, function (err, data) {
            console.log('closeResultSet success');
        })
    });
}catch(e) {
    console.log('GetResultSet e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(deviceId: string, keyPrefix: string): Promise&lt;KvStoreResultSet&gt;

Obtains the **KvStoreResultSet** object that matches the specified key prefix for a device. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| keyPrefix |string  | Yes   |Key prefix to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[KvStoreResultSet](#kvstoreresultset8)[]&gt; |Promise used to return the **KvStoreResultSet** object obtained.|

**Example**

```
let kvStore;
try {
    let resultSet;
    kvStore.getResultSet('localDeviceId', 'batch_test_string_key').then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + JSON.stringify(err));
    });
    kvStore.closeResultSet(resultSet).then((err) => {
        console.log('closeResultSet success');
    }).catch((err) => {
        console.log('closeResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('GetResultSet e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(query: Query, callback: AsyncCallback&lt;KvStoreResultSet&gt;): void

Obtains the **KvStoreResultSet** object that matches the specified **Query** object. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query  |[Query](#query8)  | Yes   |**Query** object to match.   |
| callback  |AsyncCallback&lt;[KvStoreResultSet](#kvstoreresultset8)[]&gt;  | Yes |Callback used to return the **KvStoreResultSet** object obtained.   |

**Example**

```
let kvStore;
try {
    let resultSet;
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries, async function (err, data) {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        query.deviceId('localDeviceId');
        await kvStore.getResultSet(query, async function (err, result) {
            console.log('getResultSet success');
            resultSet = result;
            await kvStore.closeResultSet(resultSet, function (err, data) {
                console.log('closeResultSet success');
            })
        });
    });
} catch(e) {
    console.log('GetResultSet e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(query: Query): Promise&lt;KvStoreResultSet&gt;

Obtains the **KvStoreResultSet** object that matches the specified **Query** object. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query  |[Query](#query8)  | Yes   |**Query** object to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[KvStoreResultSet](#kvstoreresultset8)[]&gt; |Promise used to return the **KvStoreResultSet** object obtained.|

**Example**

```
let kvStore;
try {
    let resultSet;
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
    }).catch((err) => {
        console.log('putBatch fail ' + err);
    });
    const query = new distributedData.Query();
    query.deviceId('localDeviceId');
    query.prefixKey("batch_test");
    console.log("GetResultSet " + query.getSqlLike());
    kvStore.getResultSet(query).then((result) => {
        console.log('getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('getResultSet fail ' + JSON.stringify(err));
    });
    kvStore.closeResultSet(resultSet).then((err) => {
        console.log('closeResultSet success');
    }).catch((err) => {
        console.log('closeResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('GetResultSet e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(deviceId: string, query: Query, callback: AsyncCallback&lt;KvStoreResultSet&gt;): void

Obtains the **KvStoreResultSet** object that matches the specified **Query** object for a device. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| query  |[Query](#query8)  | Yes   |**Query** object to match.   |
| callback  |AsyncCallback&lt;[KvStoreResultSet](#kvstoreresultset8)[]&gt;  | Yes |Callback used to return the **KvStoreResultSet** object obtained.   |

**Example**

```
let kvStore;
try {
    let resultSet;
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries, async function (err, data) {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        await kvStore.getResultSet('localDeviceId', query, async function (err, result) {
            console.log('getResultSet success');
            resultSet = result;
            await kvStore.closeResultSet(resultSet, function (err, data) {
                console.log('closeResultSet success');
            })
        });
    });
} catch(e) {
    console.log('GetResultSet e ' + e);
}
```


### getResultSet<sup>8+</sup> ###

getResultSet(deviceId: string, query: Query): Promise&lt;KvStoreResultSet&gt;

Obtains the **KvStoreResultSet** object that matches the specified **Query** object for a device. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device.   |
| query  |[Query](#query8)  | Yes   |**Query** object to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;[KvStoreResultSet](#kvstoreresultset8)[]&gt; |Promise used to return the **KvStoreResultSet** object obtained.|

**Example**

```
let kvStore;
try {
    let resultSet;
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries).then(async (err) => {
        console.log('GetResultSet putBatch success');
    }).catch((err) => {
        console.log('PutBatch putBatch fail ' + JSON.stringify(err));
    });
    const query = new distributedData.Query();
    query.prefixKey("batch_test");
    kvStore.getResultSet('localDeviceId', query).then((result) => {
        console.log('GetResultSet getResultSet success');
        resultSet = result;
    }).catch((err) => {
        console.log('GetResultSet getResultSet fail ' + JSON.stringify(err));
    });
    query.deviceId('localDeviceId');
    console.log("GetResultSet " + query.getSqlLike());
    kvStore.closeResultSet(resultSet).then((err) => {
        console.log('GetResultSet closeResultSet success');
    }).catch((err) => {
        console.log('GetResultSet closeResultSet fail ' + JSON.stringify(err));
    });

}catch(e) {
    console.log('GetResultSet e ' + e);
}
```


### closeResultSet<sup>8+</sup> ###

closeResultSet(resultSet: KvStoreResultSet, callback: AsyncCallback&lt;void&gt;): void

Closes the **KvStoreResultSet** object obtained by **getResultSet**. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| resultSet  |[KvStoreResultSet](#getresultset8)  | Yes   |**KvStoreResultSet** object to close.  |
| callback   |AsyncCallback&lt;void&gt;                 | Yes   |Callback used to return the result.   |

**Example**

```
let kvStore;
try {
    console.log('CloseResultSet success');
    let resultSet = null;
    kvStore.closeResultSet(resultSet, function (err, data) {
        if (err == undefined) {
            console.log('closeResultSet success');
        } else {
            console.log('closeResultSet fail');
        }
    });
}catch(e) {
    console.log('CloseResultSet e ' + e);
}
```


### closeResultSet<sup>8+</sup> ###

closeResultSet(resultSet: KvStoreResultSet): Promise&lt;void&gt;

Closes the **KvStoreResultSet** object obtained by **getResultSet**. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| resultSet  |[KvStoreResultSet](#getresultset8)  | Yes   |**KvStoreResultSet** object to close.  |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
try {
    console.log('CloseResultSet success');
    let resultSet = null;
    kvStore.closeResultSet(resultSet).then(() => {
        console.log('closeResultSet success');
    }).catch((err) => {
        console.log('closeResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('CloseResultSet e ' + e);
}
```


### getResultSize<sup>8+</sup> ###

getResultSize(query: Query, callback: AsyncCallback&lt;number&gt;): void

Obtains the number of results that matches the specified **Query** object. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query     |[Query](#query8)       | Yes   |**Query** object to match.   |
| callback  |AsyncCallback&lt;number&gt;  | Yes   |Callback used to return the number of results obtained.   |

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries, async function (err, data) {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        query.deviceId('localDeviceId');
        await kvStore.getResultSize(query, async function (err, resultSize) {
            console.log('getResultSet success');
        });
    });
} catch(e) {
    console.log('GetResultSize e ' + e);
}
```


### getResultSize<sup>8+</sup> ###

getResultSize(query: Query): Promise&lt;number&gt;

Obtains the number of results that matches the specified **Query** object. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| query     |[Query](#query8)       | Yes   |**Query** object to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;number&gt; |Promise used to return the number of results obtained.|

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
    const query = new distributedData.Query();
    query.prefixKey("batch_test");
    query.deviceId('localDeviceId');
    kvStore.getResultSize(query).then((resultSize) => {
        console.log('getResultSet success');
    }).catch((err) => {
        console.log('getResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('GetResultSize e ' + e);
}
```


### getResultSize<sup>8+</sup> ###

getResultSize(deviceId: string, query: Query, callback: AsyncCallback&lt;number&gt;): void;

Obtains the number of results that matches the specified **Query** object for a device. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string                       | Yes   |ID of the target device.   |
| query     |[Query](#query8)       | Yes   |**Query** object to match.   |
| callback  |AsyncCallback&lt;number&gt;  | Yes   |Callback used to return the number of results obtained.   |

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries, async function (err, data) {
        console.log('putBatch success');
        const query = new distributedData.Query();
        query.prefixKey("batch_test");
        await kvStore.getResultSize('localDeviceId', query, async function (err, resultSize) {
            console.log('getResultSet success');
        });
    });
} catch(e) {
    console.log('GetResultSize e ' + e);
}
```


### getResultSize<sup>8+</sup> ###

getResultSize(deviceId: string, query: Query): Promise&lt;number&gt;

Obtains the number of results that matches the specified **Query** object for a device. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string                       | Yes   |ID of the target device.   |
| query     |[Query](#query8)       | Yes   |**Query** object to match.   |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;number&gt; |Promise used to return the number of results obtained.|

**Example**

```
let kvStore;
try {
    let entries = [];
    for (var i = 0; i < 10; i++) {
        var key = 'batch_test_string_key';
        var entry = {
            key : key + i,
            value : {
                type : distributedData.ValueType.STRING,
                value : 'batch_test_string_value'
            }
        }
        entries.push(entry);
    }
    kvStore.putBatch(entries).then(async (err) => {
        console.log('putBatch success');
    }).catch((err) => {
        console.log('putBatch fail ' + JSON.stringify(err));
    });
    var query = new distributedData.Query();
    query.prefixKey("batch_test");
    kvStore.getResultSize('localDeviceId', query).then((resultSize) => {
        console.log('getResultSet success');
    }).catch((err) => {
        console.log('getResultSet fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('GetResultSize e ' + e);
}
```


### removeDeviceData<sup>8+</sup> ###

removeDeviceData(deviceId: string, callback: AsyncCallback&lt;void&gt;): void

Removes data of a device from this KV store. This method uses an asynchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string                       | Yes   |ID of the target device. |
| callback  |AsyncCallback&lt;void&gt;    | Yes   |Callback used to return the result.   |

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value-string-001';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT, async function (err,data) {
        console.log('RemoveDeviceData  put success');
        const deviceid = 'no_exist_device_id';
        await kvStore.removeDeviceData(deviceid, async function (err,data) {
            if (err == undefined) {
                console.log('removeDeviceData success');
            } else {
                console.log('removeDeviceData fail');
                await kvStore.get('localDeviceId', KEY_TEST_STRING_ELEMENT, async function (err,data) {
                    console.log('RemoveDeviceData get success');
                });
            }
        });
    });
}catch(e) {
    console.log('RemoveDeviceData e ' + e);
}
```


### removeDeviceData<sup>8+</sup> ###

removeDeviceData(deviceId: string): Promise&lt;void&gt;

Removes data of a device from this KV store. This method uses a promise to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.DistributedKVStore

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceId  |string  | Yes   |ID of the target device. |

**Return value**

| Type   | Description      |
| ------  | -------   |
|Promise&lt;void&gt; |Promise used to return the result.|

**Example**

```
let kvStore;
const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value-string-001';
try {
    kvStore.put(KEY_TEST_STRING_ELEMENT, VALUE_TEST_STRING_ELEMENT).then((err) => {
        console.log('RemoveDeviceData put success');
    }).catch((err) => {
        console.log('RemoveDeviceData put fail ' + JSON.stringify(err));
    });
    const deviceid = 'no_exist_device_id';
    kvStore.removeDeviceData(deviceid).then((err) => {
        console.log('removeDeviceData success');
    }).catch((err) => {
        console.log('removeDeviceData fail ' + JSON.stringify(err));
    });
    kvStore.get('localDeviceId', KEY_TEST_STRING_ELEMENT).then((data) => {
        console.log('RemoveDeviceData get success data:' + data);
    }).catch((err) => {
        console.log('RemoveDeviceData get fail ' + JSON.stringify(err));
    });
}catch(e) {
    console.log('RemoveDeviceData e ' + e);
}
```


### sync<sup>8+</sup> ###

sync(deviceIdList: string[], mode: SyncMode, allowedDelayMs?: number): void

Manually triggers KV store synchronization synchronously.
**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| deviceIdList    |string[]               | Yes   |IDs of the devices to be synchronized.|
| mode            |[SyncMode](#syncmode)  | Yes   |Data synchronization mode, which can be **PUSH**, **PULL**, or **PUSH_PULL**. |
| allowedDelayMs  |number                 | No   |Allowed synchronization delay time, in ms. |

**Example**

```
let kvStore;
const KEY_TEST_SYNC_ELEMENT = 'key_test_sync';
const VALUE_TEST_SYNC_ELEMENT = 'value-string-001';
try {
    kvStore.on('syncComplete', function (data) {
        console.log('Sync dataChange');
    });
    kvStore.put(KEY_TEST_SYNC_ELEMENT + 'testSync101', VALUE_TEST_SYNC_ELEMENT, function (err,data) {
        console.log('Sync put success');
        const devices = ['deviceList'];
        const mode = distributedData.SyncMode.PULL_ONLY;
        kvStore.sync(devices, mode);
    });
}catch(e) {
    console.log('Sync e' + e);
}
```

### on<sup>8+</sup> ###

on(event: 'syncComplete', syncCallback: Callback&lt;Array&lt;[string, number]&gt;&gt;): void

Subscribes to the synchronization completion events. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| event    |'syncComplete'      | Yes   |Event triggered when the synchronization is complete.|
| syncCallback            |Callback<Array&lt;<[string, number]&gt; | Yes   |Callback used to return the synchronization result. |

**Example**

```
const KEY_TEST_FLOAT_ELEMENT = 'key_test_float';
const VALUE_TEST_FLOAT_ELEMENT = 321.12;
try {
    kvStore.on('syncComplete', function (data) {
        console.log('syncComplete ' + data)
    });
    kvStore.put(KEY_TEST_FLOAT_ELEMENT, VALUE_TEST_FLOAT_ELEMENT).then((data) => {
        console.log('syncComplete put success');
    }).catch((error) => {
        console.log('syncComplete put fail ' + error);
    });
}catch(e) {
    console.log('syncComplete put e ' + e);
}
```


### off<sup>8+</sup> ###

off(event: 'syncComplete', syncCallback?: Callback&lt;Array&lt;[string, number]&gt;&gt;): void

Unsubscribes from the synchronization completion events. This method uses a synchronous callback to return the result.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

**Parameters**

| Name | Type| Mandatory | Description                   |
| -----  | ------   | ----  | ----------------------- |
| event         |'syncComplete'                           | Yes   |Event triggered when the synchronization is complete.|
| syncCallback  |Callback<Array&lt;[string, number]&gt;&gt; | No   |Callback used to return the synchronization result. |

**Example**

```
let kvStore;
try {
    const func = function (data) {
        console.log('syncComplete ' + data)
    };
    kvStore.on('syncComplete', func);
    kvStore.off('syncComplete', func);
}catch(e) {
    console.log('syncComplete e ' + e);
}
```


## SyncMode

Defines the synchronization mode.

**System capability**: SystemCapability.DistributedDataManager.KVStore.Core

| Name      | Default Value    | Description                   |
| -----      | ------    | ----------------------- |
| PULL_ONLY  |0          |Pull data from the peer end to the local end only.|
| PUSH_ONLY  |1          |Push data from the local end to the peer end only.|
| PUSH_PULL  |2          |Push data from the local end to the peer end and then pull data from the peer end to the local end.|