From dafd5a6202dde45d0ec3a7111b1be20136a8887d Mon Sep 17 00:00:00 2001 From: Annie_wang <annie.wangli@huawei.com> Date: Fri, 19 Aug 2022 16:55:06 +0800 Subject: [PATCH] update docs Signed-off-by: Annie_wang <annie.wangli@huawei.com> --- .../database-relational-guidelines.md | 122 ++++++------------ 1 file changed, 41 insertions(+), 81 deletions(-) diff --git a/en/application-dev/database/database-relational-guidelines.md b/en/application-dev/database/database-relational-guidelines.md index 843ac83b9f..a2aacf698c 100644 --- a/en/application-dev/database/database-relational-guidelines.md +++ b/en/application-dev/database/database-relational-guidelines.md @@ -7,7 +7,7 @@ A relational database (RDB) store allows you to operate local data with or witho ## Available APIs -For details about RDB APIs, see [Relational Database](../reference/apis/js-apis-data-rdb.md). +Most of the RDB store APIs are asynchronous interfaces, which can use a callback or promise to return the result. This document uses the promise-based APIs as an example. For details about the APIs, see [Relational Database](../reference/apis/js-apis-data-rdb.md). ### Creating or Deleting an RDB Store @@ -17,10 +17,8 @@ The following table describes the APIs available for creating and deleting an RD | API| Description| | -------- | -------- | -|getRdbStore(context: Context, config: StoreConfig, version: number, callback: AsyncCallback<RdbStore>): void| Obtains an RDB store. This API uses a callback to return the result. You can set parameters for the RDB store based on service requirements, and then call APIs to perform data operations.<br>- **context**: context of the application or function.<br>- **config**: configuration of the RDB store.<br>- **version**: RDB version.<br>- **callback**: callback invoked to return the RDB store obtained.| -|getRdbStore(context: Context, config: StoreConfig, version: number): Promise<RdbStore> | Obtains an RDB store. This API uses a promise to return the result. You can set parameters for the RDB store based on service requirements, and then call APIs to perform data operations.<br>- **context**: context of the application or function.<br>- **config**: configuration of the RDB store.<br>- **version**: RDB version.| -|deleteRdbStore(context: Context, name: string, callback: AsyncCallback<void> ): void | Deletes an RDB store. This API uses a callback to return the result. <br>- **context**: context of the application or function.<br>- **name**: RDB store to delete.<br>- **callback**: callback invoked to return the result.| -| deleteRdbStore(context: Context, name: string): Promise<void> | Deletes an RDB store. This API uses a promise to return the result.<br>- **context**: context of the application or function.<br>- **name**: RDB store to delete.| +|getRdbStore(context: Context, config: StoreConfig, version: number): Promise<RdbStore> | Obtains an RDB store. This API uses a promise to return the result. You can set parameters for the RDB store based on service requirements and call APIs to perform data operations.<br>- **context**: context of the application or function.<br>- **config**: configuration of the RDB store.<br>- **version**: version of the RDB store.| +| deleteRdbStore(context: Context, name: string): Promise<void> | Deletes an RDB store. This API uses a promise to return the result.<br>- **context**: context of the application or function.<br>- **name**: name of the RDB store to delete.| ### Managing Data in an RDB Store @@ -30,34 +28,31 @@ The RDB provides APIs for inserting, deleting, updating, and querying data in th The RDB provides APIs for inserting data through a **ValuesBucket** in a data table. If the data is inserted, the row ID of the data inserted will be returned; otherwise, **-1** will be returned. - **Table 2** APIs for inserting data + **Table 2** API for inserting data | Class| API| Description| | -------- | -------- | -------- | - | RdbStore | insert(table: string, values: ValuesBucket, callback: AsyncCallback<number>):void | Inserts a row of data into a table. This API uses a callback to return the result.<br>- **table**: name of the target table.<br>- **values**: data to be inserted into the table.<br>- **callback**: callback invoked to return the result. If the operation is successful, the row ID will be returned; otherwise, **-1** will be returned.| - | RdbStore | insert(table: string, values: ValuesBucket): Promise<number> | Inserts a row of data into a table. This API uses a promise to return the result.<br>- **table**: name of the target table.<br>- **values**: data to be inserted into the table.| + | RdbStore | insert(table:string,values:ValuesBucket):Promise<number> | Inserts a row of data into a table. This API uses a promise to return the result.<br>If the operation is successful, the row ID will be returned; otherwise, **-1** will be returned.<br>- **table**: name of the target table.<br>- **values**: data to be inserted into the table.| - **Updating data** Call the **update()** method to pass new data and specify the update conditions by using **RdbPredicates**. If the data is updated, the number of rows of the updated data will be returned; otherwise, **0** will be returned. - **Table 3** APIs for updating data + **Table 3** API for updating data | Class| API| Description| | -------- | -------- | -------- | - | RdbStore | update(values: ValuesBucket, predicates: RdbPredicates, callback: AsyncCallback<number>):void | Updates data in the RDB store based on the specified **RdbPredicates** object. This API uses a callback to return the result.<br>- **values**: data to update, which is stored in a **ValuesBucket**.<br>- **predicates**: conditions for updating data.<br>- **callback**: callback invoked to return the number of rows updated.| - | RdbStore | update(values: ValuesBucket, predicates: RdbPredicates): Promise<number> | Updates data in the RDB store based on the specified **RdbPredicates** object. This API uses a promise to return the result.<br>- **values**: data to update, which is stored in a **ValuesBucket**.<br>- **predicates**: conditions for updating data.| + | RdbStore | update(values:ValuesBucket,predicates:RdbPredicates):Promise<number> | Updates data based on the specified **RdbPredicates** object. This API uses a promise to return the result.<br>Return value: number of rows updated.<br>- **values**: data to update, which is stored in **ValuesBucket**.<br>- **predicates**: conditions for updating data. | - **Deleting data** Call the **delete()** method to delete data meeting the conditions specified by **RdbPredicates**. If the data is deleted, the number of rows of the deleted data will be returned; otherwise, **0** will be returned. - **Table 4** APIs for deleting data + **Table 4** API for deleting data | Class| API| Description| | -------- | -------- | -------- | - | RdbStore | delete(predicates: RdbPredicates, callback: AsyncCallback<number>):void | Deletes data from the RDB store based on the specified **RdbPredicates** object. This API uses an asynchronous callback to return the result.<br>- **predicates**: conditions for deleting data.<br>- **callback**: callback invoked to return the number of rows updated.| - | RdbStore | delete(predicates: RdbPredicates): Promise<number> | Deletes data from the RDB store based on the specified **RdbPredicates** object. This API uses a promise to return the result.<br>- **predicates**: conditions for deleting data.| + | RdbStore | delete(predicates:RdbPredicates):Promise<number> | Deletes data from the RDB store based on the specified **RdbPredicates** object. This API uses a promise to return the result.<br>Return value: number of rows updated.<br>- **predicates**: conditions for deleting data. | - **Querying data** @@ -70,53 +65,31 @@ The RDB provides APIs for inserting, deleting, updating, and querying data in th | Class| API| Description| | -------- | -------- | -------- | - | RdbStore | query(predicates: RdbPredicates, columns: Array<string>, callback: AsyncCallback<ResultSet>): void | Queries data in the RDB store based on the specified **RdbPredicates** object. This API uses a callback to return the result.<br>- **predicates**: conditions for querying data.<br>- **columns**: columns to query. If this parameter is not specified, the query applies to all columns.<br>- **callback**: callback invoked to return the result. If the operation is successful, a **ResultSet** object will be returned.| - | RdbStore | query(predicates: RdbPredicates, columns?: Array<string>): Promise<ResultSet> | Queries data in the RDB store based on the specified **RdbPredicates** object. This API uses a promise to return the result.<br>- **predicates**: conditions for querying data.<br>- **columns**: columns to query. If this parameter is not specified, the query applies to all columns.| - | RdbStore | querySql(sql: string, bindArgs: Array<ValueType>, callback: AsyncCallback<ResultSet>):void | Queries data in the RDB store using the specified SQL statement. This API uses a callback to return the result.<br>- **sql**: SQL statement.<br>- **bindArgs**: arguments in the SQL statement.<br>- **callback**: callback invoked to return the result. If the operation is successful, a **ResultSet** object will be returned.| - | RdbStore | querySql(sql: string, bindArgs?: Array<ValueType>):Promise<ResultSet> | Queries data in the RDB store using the specified SQL statement. This API uses a promise to return the result.<br>- **sql**: SQL statement.<br>- **bindArgs**: arguments in the SQL statement.| + | RdbStore | query(predicates:RdbPredicates,columns?:Array<string>):Promise<ResultSet> | Queries data from the RDB store based on specified conditions. This API uses a promise to return the result.<br>- **predicates**: conditions for querying data.<br>- **columns**: columns to query. If this parameter is not specified, the query applies to all columns.| + | RdbStore | querySql(sql:string,bindArgs?:Array<ValueType>):Promise<ResultSet> | Queries data using the specified SQL statement. This API uses a promise to return the result.<br>- **sql**: SQL statement.<br>- **bindArgs**: arguments in the SQL statement.| ### Using Predicates The RDB provides **RdbPredicates** for you to set database operation conditions. +The following lists common predicates. For more information about predicates, see [**RdbPredicates**](../reference/apis/js-apis-data-rdb.md#rdbpredicates). + **Table 6** APIs for using RDB store predicates | Class| API| Description| | -------- | -------- | -------- | -| RdbPredicates |inDevices(devices: Array\<string>): RdbPredicates | Specifies remote devices on the network with RDB stores to be synchronized.<br>- **devices**: IDs of the remote devices on the network.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates |inAllDevices(): RdbPredicates | Connects to all remote devices on the network with RDB stores to be synchronized.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | equalTo(field: string, value: ValueType): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **ValueType** and value equal to the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | notEqualTo(field: string, value: ValueType): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **ValueType** and value not equal to the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | beginWrap(): RdbPredicates | Adds a left parenthesis to the **RdbPredicates**.<br>- **RdbPredicates**: returns a **RdbPredicates** with a left parenthesis.| -| RdbPredicates | endWrap(): RdbPredicates | Adds a right parenthesis to the **RdbPredicates**.<br>- **RdbPredicates**: returns a **RdbPredicates** with a right parenthesis.| -| RdbPredicates | or(): RdbPredicates | Adds the OR condition to the **RdbPredicates**.<br>- **RdbPredicates**: returns a **RdbPredicates** with the OR condition.| -| RdbPredicates | and(): RdbPredicates | Adds the AND condition to the **RdbPredicates**.<br>- **RdbPredicates**: returns a **RdbPredicates** with the AND condition.| -| RdbPredicates | contains(field: string, value: string): RdbPredicates | Sets the **RdbPredicates** to match a string containing the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified string.| -| RdbPredicates | beginsWith(field: string, value: string): RdbPredicates | Sets the **RdbPredicates** to match a string that starts with the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | endsWith(field: string, value: string): RdbPredicates | Sets the **RdbPredicates** to match a string that ends with the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | isNull(field: string): RdbPredicates | Sets the **RdbPredicates** to match the field whose value is null.<br>- **field**: column name in the database table.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | isNotNull(field: string): RdbPredicates | Sets the **RdbPredicates** to match the field whose value is not null.<br>- **field**: column name in the database table.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | like(field: string, value: string): RdbPredicates | Sets the **RdbPredicates** to match a string that is similar to the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | glob(field: string, value: string): RdbPredicates | Sets the **RdbPredicates** to match the specified string.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | between(field: string, low: ValueType, high: ValueType): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **ValueType** and value within the specified range.<br>- **field**: column name in the database table.<br>- **low**: minimum value that matches the **RdbPredicates**.<br>- **high**: maximum value that matches the **RdbPredicates**.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | notBetween(field: string, low: ValueType, high: ValueType): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **ValueType** and value out of the specified range.<br>- **field**: column name in the database table.<br>- **low**: minimum value that matches the **RdbPredicates**.<br>- **high**: maximum value that matches the **RdbPredicates**.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | greaterThan(field: string, value: ValueType): RdbPredicatesgr | Sets the **RdbPredicates** to match the field with data type **ValueType** and value greater than the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | lessThan(field: string, value: ValueType): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **ValueType** and value less than the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | greaterThanOrEqualTo(field: string, value: ValueType): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **ValueType** and value greater than or equal to the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | lessThanOrEqualTo(field: string, value: ValueType): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **ValueType** and value less than or equal to the specified value.<br>- **field**: column name in the database table.<br>- **value**: value specified.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | orderByAsc(field: string): RdbPredicates | Sets the **RdbPredicates** to match the column with values sorted in ascending order.<br>- **field**: column name in the database table.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | orderByDesc(field: string): RdbPredicates | Sets the **RdbPredicates** to match the column with values sorted in descending order.<br>- **field**: column name in the database table.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | distinct(): RdbPredicates | Sets the **RdbPredicates** to filter out duplicate records.<br>- **RdbPredicates**: returns a **RdbPredicates** object that can filter out duplicate records.| -| RdbPredicates | limitAs(value: number): RdbPredicates | Sets the **RdbPredicates** to specify the maximum number of records.<br>- **value**: maximum number of records.<br>- **RdbPredicates**: returns a **RdbPredicates** object that can be used to set the maximum number of records.| -| RdbPredicates | offsetAs(rowOffset: number): RdbPredicates | Sets the **RdbPredicates** to specify the start position of the returned result.<br>- **rowOffset**: start position of the returned result. The value is a positive integer.<br>- **RdbPredicates**: returns a **RdbPredicates** object that specifies the start position of the returned result.| -| RdbPredicates | groupBy(fields: Array<string>): RdbPredicates | Sets the **RdbPredicates** to group rows that have the same value into summary rows.<br>- **fields**: names of the columns grouped for querying data.<br>- **RdbPredicates**: returns a **RdbPredicates** object that groups rows with the same value.| -| RdbPredicates | indexedBy(indexName: string): RdbPredicates | Sets the **RdbPredicates** to specify the index column.<br>- **indexName**: name of the index column.<br>- **RdbPredicates**: returns a **RdbPredicates** object that specifies the index column.| -| RdbPredicates | in(field: string, value: Array<ValueType>): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **Array<ValueType>** and value within the specified range.<br>- **field**: column name in the database table.<br>- **value**: array of **ValueType** to match.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| -| RdbPredicates | notIn(field: string, value: Array<ValueType>): RdbPredicates | Sets the **RdbPredicates** to match the field with data type **Array<ValueType>** and value out of the specified range.<br>- **field**: column name in the database table.<br>- **value**: array of **ValueType** to match.<br>- **RdbPredicates**: returns a **RdbPredicates** object that matches the specified field.| +| RdbPredicates | equalTo(field:string,value:ValueType):RdbPredicates | Sets an **RdbPredicates** to match the field with data type **ValueType** and value equal to the specified value.<br>- **field**: column name in the database table.<br>- **value**: value to match the **RdbPredicates**.<br>- **RdbPredicates**: **RdbPredicates** object that matches the specified field.| +| RdbPredicates | notEqualTo(field:string,value:ValueType):RdbPredicates | Sets an **RdbPredicates** to match the field with data type **ValueType** and value not equal to the specified value.<br>- **field**: column name in the database table.<br>- **value**: value to match the **RdbPredicates**.<br>- **RdbPredicates**: **RdbPredicates** object that matches the specified field.| +| RdbPredicates | or():RdbPredicates | Adds the OR condition to the **RdbPredicates**.<br>- **RdbPredicates**: **RdbPredicates** with the OR condition.| +| RdbPredicates | and():RdbPredicates | Adds the AND condition to the **RdbPredicates**.<br>- **RdbPredicates**: **RdbPredicates** with the AND condition.| +| RdbPredicates | contains(field:string,value:string):RdbPredicates | Sets an **RdbPredicates** to match a string containing the specified value.<br>- **field**: column name in the database table.<br>- **value**: value to match the **RdbPredicates**.<br>- **RdbPredicates**: **RdbPredicates** object that matches the specified field.| + ### Using the Result Set -A result set can be regarded as a row of data in the queried results. It allows you to traverse and access the data you have queried. The following table describes the external APIs of **ResultSet**. +A result set can be regarded as a row of data in the queried results. It allows you to traverse and access the data you have queried. + +For details about how to use result set APIs, see [Result Set](../reference/apis/js-apis-data-resultset.md). > **NOTICE**<br> > After a result set is used, you must call the **close()** method to close it explicitly. @@ -125,19 +98,12 @@ A result set can be regarded as a row of data in the queried results. It allows | Class| API| Description| | -------- | -------- | -------- | -| ResultSet | goTo(offset:number): boolean | Moves the result set forwards or backwards by the specified offset relative to its current position.| -| ResultSet | goToRow(position: number): boolean | Moves the result set to the specified row.| -| ResultSet | goToNextRow(): boolean | Moves the result set to the next row.| -| ResultSet | goToPreviousRow(): boolean | Moves the result set to the previous row.| -| ResultSet | getColumnIndex(columnName: string): number | Obtains the column index based on the specified column name.| -| ResultSet | getColumnName(columnIndex: number): string | Obtains the column name based on the specified column index.| -| ResultSet | goToFirstRow(): boolean | Moves to the first row of the result set.| -| ResultSet | goToLastRow(): boolean | Moves to the last row of the result set.| -| ResultSet | getString(columnIndex: number): string | Obtains the value in the specified column of the current row, in a string.| -| ResultSet | getBlob(columnIndex: number): Uint8Array | Obtains the values in the specified column of the current row, in a byte array.| -| ResultSet | getDouble(columnIndex: number): number | Obtains the values in the specified column of the current row, in double.| -| ResultSet | isColumnNull(columnIndex: number): boolean | Checks whether the value in the specified column of the current row is null.| -| ResultSet | close(): void | Closes the result set.| +| ResultSet | goToFirstRow():boolean | Moves to the first row of the result set.| +| ResultSet | getString(columnIndex:number):string | Obtains the value in the form of a string based on the specified column and current row.| +| ResultSet | getBlob(columnIndex:number):Uint8Array | Obtains the value in the form of a byte array based on the specified column and the current row.| +| ResultSet | getDouble(columnIndex:number):number | Obtains the value in the form of double based on the specified column and current row.| +| ResultSet | getLong(columnIndex:number):number | Obtains the value in the form of a long integer based on the specified column and current row.| +| ResultSet | close():void | Closes the result set.| @@ -147,32 +113,29 @@ A result set can be regarded as a row of data in the queried results. It allows **Setting Distributed Tables** -**Table 8** APIs for setting distributed tables +**Table 8** API for setting distributed tables | Class| API| Description| | -------- | -------- | -------- | -| RdbStore | setDistributedTables(tables: Array\<string>, callback: AsyncCallback\<void>): void | Sets a list of distributed tables. This API uses a callback to return the result.<br>- **tables**: names of the distributed tables to set.<br>- **callback**: callback invoked to return the result.| -| RdbStore | setDistributedTables(tables: Array\<string>): Promise\<void> | Sets a list of distributed tables. This API uses a promise to return the result.<br>- **tables**: names of the distributed tables to set.| +| RdbStore | setDistributedTables(tables: Array\<string>): Promise\<void> | Sets distributed tables. This API uses a promise to return the result.<br>- **tables**: names of the distributed tables to set.| **Obtaining the Distributed Table Name for a Remote Device** You can obtain the distributed table name for a remote device based on the local table name. The distributed table name can be used to query the RDB store of the remote device. -**Table 9** APIs for obtaining the distributed table name of a remote device +**Table 9** API for obtaining the distributed table name of a remote device | Class| API| Description| | -------- | -------- | -------- | -| RdbStore | obtainDistributedTableName(device: string, table: string, callback: AsyncCallback\<string>): void | Obtains the distributed table name for a remote device based on the local table name. The distributed table name is required when the database of a remote device is queried. This API uses an asynchronous callback to return the result.<br>- **device**: remote device.<br>- **table**: local table name.<br>- **callback**: callback used to return the result. If the operation is successful, the distributed table name of the remote device will be returned. | -| RdbStore | obtainDistributedTableName(device: string, table: string): Promise\<string> | Obtains the distributed table name for a remote device based on the local table name. The distributed table name is used to query the RDB store of the remote device. This API uses a promise to return the result.<br>- **device**: remote device.<br>- **table**: local table name.| +| RdbStore | obtainDistributedTableName(device: string, table: string): Promise\<string> | Obtains the distributed table name for a remote device based on the local table name. The distributed table name is required when the RDB store of a remote device is queried. This API uses a promise to return the result.<br>- **device**: remote device.<br>- **table**: local table name.| **Synchronizing Data Between Devices** -**Table 10** APIs for synchronizing data between devices +**Table 10** API for synchronizing data between devices | Class| API| Description| | -------- | -------- | -------- | -| RdbStore | sync(mode: SyncMode, predicates: RdbPredicates, callback: AsyncCallback\<Array\<[string, number]>>): void | Synchronizes data between devices. This API uses a callback to return the result.<br>- **mode**: data synchronization mode. **SYNC_MODE_PUSH** means to push data from the local device to a remote device. **SYNC_MODE_PULL** means to pull data from a remote device to the local device.<br>- **predicates**: data and devices to be synchronized.<br>- **callback**: callback invoked to return the result. In the result, **string** indicates the device ID, and **number** indicates the synchronization status of each device. The value **0** indicates a success, and other values indicate a failure.| -| RdbStore | sync(mode: SyncMode, predicates: RdbPredicates): Promise\<Array\<[string, number]>> | Synchronizes data between devices. This API uses a promise to return the result.<br>- **mode**: data synchronization mode. **SYNC_MODE_PUSH** means to push data from the local device to a remote device. **SYNC_MODE_PULL** means to pull data from a remote device to the local device.<br>- **predicates**: data and devices to be synchronized. | +| RdbStore | sync(mode: SyncMode, predicates: RdbPredicates): Promise\<Array\<[string, number]>> | Synchronizes data between devices. This API uses a promise to return the result.<br>- **mode**: synchronization mode. **SYNC_MODE_PUSH** means to push data from the local device to a remote device. **SYNC_MODE_PULL** means to pull data from a remote device to the local device.<br>- **predicates**: specifies the data and devices to synchronize.<br>- **string**: device ID. <br>- **number**: synchronization status of each device. The value **0** indicates a successful synchronization. Other values indicate a synchronization failure. | **Registering an RDB Store Observer** @@ -188,27 +151,25 @@ You can obtain the distributed table name for a remote device based on the local | Class| API| Description| | -------- | -------- | -------- | -| RdbStore |off(event:'dataChange', type: SubscribeType, observer: Callback\<Array\<string>>): void;| Unregisters the observer of the specified type for the RDB store. This API uses a callback to return the result.<br>- **type**: subscription type. **SUBSCRIBE_TYPE_REMOTE** means to subscribe to remote data changes.<br>- **observer**: observer to unregister.| +| RdbStore |off(event:'dataChange', type: SubscribeType, observer: Callback\<Array\<string>>): void;| Unregisters the observer of the specified type for the RDB store. This method uses a callback to return the result.<br>- **type**: subscription type. **SUBSCRIBE_TYPE_REMOTE** means to subscribe to remote data changes.<br>- **observer**: observer to unregister.| ### Backing Up and Restoring an RDB Store **Backing Up an RDB Store** -**Table 13** APIs for backing up an RDB store +**Table 13** API for backing up an RDB store | Class| API| Description| | -------- | -------- | -------- | -| RdbStore |backup(destName:string, callback: AsyncCallback<void>):void| Backs up an RDB store. This API uses an asynchronous callback to return the result.<br>- **destName**: name of the RDB backup file.<br>- **callback**: callback invoked to return the result.| | RdbStore |backup(destName:string): Promise<void>| Backs up an RDB store. This API uses a promise to return the result.<br>- **destName**: name of the RDB backup file.| **Restoring an RDB Store** -**Table 14** APIs for restoring an RDB store +**Table 14** API for restoring an RDB store | Class| API| Description| | -------- | -------- | -------- | -| RdbStore |restore(srcName:string, callback: AsyncCallback<void>):void| Restores an RDB store using a backup file. This API uses an asynchronous callback to return the result.<br>- **srcName**: name of the RDB backup file.<br>- **callback**: callback invoked to return the result.| -| RdbStore |restore(srcName:string): Promise<void>| Restores an RDB store using a backup file. This API uses a promise to return the result.<br>- **srcName**: name of the RDB backup file.| +| RdbStore |restore(srcName:string): Promise<void>| Restores an RDB store from a backup file. This API uses a promise to return the result.<br>- **srcName**: name of the backup file used to restore the RDB store.| **Transaction** @@ -236,7 +197,7 @@ Table 15 Transaction APIs import data_rdb from '@ohos.data.rdb' const CREATE_TABLE_TEST = "CREATE TABLE IF NOT EXISTS test (" + "id INTEGER PRIMARY KEY AUTOINCREMENT, " + "name TEXT NOT NULL, " + "age INTEGER, " + "salary REAL, " + "blobType BLOB)"; - const STORE_CONFIG = {name: "rdbstore.db",} + const STORE_CONFIG = {name: "rdbstore.db"} data_rdb.getRdbStore(this.context, STORE_CONFIG, 1, function (err, rdbStore) { rdbStore.executeSql(CREATE_TABLE_TEST) console.info('create table done.') @@ -253,7 +214,7 @@ Table 15 Transaction APIs ```js var u8 = new Uint8Array([1, 2, 3]) - const valueBucket = {"name": "Tom", "age": 18, "salary": 100.5, "blobType": u8,} + const valueBucket = {"name": "Tom", "age": 18, "salary": 100.5, "blobType": u8} let insertPromise = rdbStore.insert("test", valueBucket) ``` @@ -280,7 +241,7 @@ Table 15 Transaction APIs const blobType = resultSet.getBlob(resultSet.getColumnIndex("blobType")) resultSet.close() }) - ``` + ``` 4. Set the distributed tables to be synchronized. @@ -396,4 +357,3 @@ Table 15 Transaction APIs console.info('Restore failed, err: ' + err) }) ``` - -- GitLab