js-apis-data-resultset.md

# Result Set

A result set is a set of results returned after the relational database (RDB) query APIs are called. You can use the **resultset** APIs to obtain required data.

> **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.


## Usage

You need to use [RdbStore.query()](js-apis-data-rdb.md#query) to obtain a **resultSet** object.

```js
import dataRdb from '@ohos.data.rdb';
let predicates = new dataRdb.RdbPredicates("EMPLOYEE")
predicates.equalTo("AGE", 18)
let promise = rdbStore.query(predicates, ["ID", "NAME", "AGE", "SALARY", "CODES"])
promise.then((resultSet) => {
    console.log(TAG + "resultSet columnNames:" + resultSet.columnNames);
    console.log(TAG + "resultSet columnCount:" + resultSet.columnCount);})
```

## ResultSet

Provides methods to access the result set, which is obtained by querying the RDB store.


### Attributes

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

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| columnNames | Array&lt;string&gt; | Yes| Names of all columns in the result set.|
| columnCount | number | Yes| Number of columns in the result set.|
| rowCount | number | Yes| Number of rows in the result set.|
| rowIndex | number | Yes| Index of the current row in the result set.|
| isAtFirstRow | boolean | Yes| Whether the cursor is in the first row of the result set.|
| isAtLastRow | boolean | Yes| Whether the cursor is in the last row of the result set.|
| isEnded | boolean | Yes| Whether the cursor is after the last row of the result set.|
| isStarted | boolean | Yes| Whether the cursor has been moved.|
| isClosed | boolean | Yes| Whether the result set is closed.|


### getColumnIndex

getColumnIndex(columnName: string): number

Obtains the column index based on the column name.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | columnName | string | Yes| Column name specified.|

**Return value**
  | Type| Description|
  | -------- | -------- |
  | number | Index of the column obtained.|

**Example**
  ```js
  resultSet.goToFirstRow()
  const id = resultSet.getLong(resultSet.getColumnIndex("ID"))
  const name = resultSet.getString(resultSet.getColumnIndex("NAME"))
  const age = resultSet.getLong(resultSet.getColumnIndex("AGE"))
  const salary = resultSet.getDouble(resultSet.getColumnIndex("SALARY"))
  ```


### getColumnName

getColumnName(columnIndex: number): string

Obtains the column name based on the column index.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | columnIndex | number | Yes| Column index specified.|

**Return value**
  | Type| Description|
  | -------- | -------- |
  | string | Column name obtained.|

**Example**
  ```js
  const id = resultSet.getColumnName(0)
  const name = resultSet.getColumnName(1)
  const age = resultSet.getColumnName(2)
  ```


### goTo

goTo(offset:number): boolean

Moves the cursor to the row based on the specified offset.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | offset | number | Yes| Offset relative to the current position.|

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

**Example**
  ```js
  let predicatesgoto = new dataRdb.RdbPredicates("EMPLOYEE")
  let promisequerygoto = rdbStore.query(predicatesgoto, ["ID", "NAME", "AGE", "SALARY", "CODES"])
  promisequerygoto.then((resultSet) {
      resultSet.goTo(1)
      resultSet.close()
  }).catch((err) => {
      console.log('query failed')
  })
  ```


### goToRow

goToRow(position: number): boolean

Moves the cursor to the specified row in the result set.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | position | number | Yes| Position to which the cursor is to be moved.|

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

**Example**
  ```js
  let predicatesgotorow = new dataRdb.RdbPredicates("EMPLOYEE")
  let promisequerygotorow = rdbStore.query(predicatesgotorow, ["ID", "NAME", "AGE", "SALARY", "CODES"])
  promisequerygotorow.then((resultSet) {
      resultSet.goToRow(5)
      resultSet.close()
  }).catch((err) => {
      console.log('query failed')
  })
  ```


### goToFirstRow

goToFirstRow(): boolean


Moves the cursor to the first row of the result set.

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

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

**Example**
  ```js
  let predicatesgoFirst = new dataRdb.RdbPredicates("EMPLOYEE")
  let promisequerygoFirst = rdbStore.query(predicatesgoFirst, ["ID", "NAME", "AGE", "SALARY", "CODES"])
  promisequerygoFirst.then((resultSet) {
      resultSet.goToFirstRow()
      resultSet.close()
  }).catch((err) => {
      console.log('query failed')
  })
  ```


### goToLastRow

goToLastRow(): boolean

Moves the cursor to the last row of the result set.

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

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

**Example**
  ```js
  let predicatesgoLast = new dataRdb.RdbPredicates("EMPLOYEE")
  let promisequerygoLast = rdbStore.query(predicatesgoLast, ["ID", "NAME", "AGE", "SALARY", "CODES"])
  promisequerygoLast.then((resultSet) {
      resultSet.goToLastRow()
      resultSet.close()
  }).catch((err) => {
      console.log('query failed')
  })
  ```


### goToNextRow

goToNextRow(): boolean

Moves the cursor to the next row in the result set.

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

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

**Example**
  ```js
  let predicatesgoNext = new dataRdb.RdbPredicates("EMPLOYEE")
  let promisequerygoNext = rdbStore.query(predicatesgoNext, ["ID", "NAME", "AGE", "SALARY", "CODES"])
  promisequerygoNext.then((resultSet) {
      resultSet.goToNextRow()
      resultSet.close()
  }).catch((err) => {
      console.log('query failed')
  })
  ```


### goToPreviousRow

goToPreviousRow(): boolean

Moves the cursor to the previous row in the result set.

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

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

**Example**
  ```js
  let predicatesgoPrev = new dataRdb.RdbPredicates("EMPLOYEE")
  let promisequerygoPrev = rdbStore.query(predicatesgoPrev, ["ID", "NAME", "AGE", "SALARY", "CODES"])
  promisequerygoPrev.then((resultSet) {
      resultSet.goToPreviousRow()
      resultSet.close()
  }).catch((err) => {
      console.log('query failed')
  })
  ```


### getBlob

getBlob(columnIndex: number): Uint8Array

Obtains the value in the specified column in the current row as a byte array.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | columnIndex | number | Yes| Index of the specified column, starting from 0.|

**Return value**
  | Type| Description|
  | -------- | -------- |
  | Uint8Array | Value in the specified column as a byte array.|

**Example**
  ```js
  const codes = resultSet.getBlob(resultSet.getColumnIndex("CODES"))
  ```


### getString

getString(columnIndex: number): string

Obtains the value in the specified column in the current row as a string.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | columnIndex | number | Yes| Index of the specified column, starting from 0.|

**Return value**
  | Type| Description|
  | -------- | -------- |
  | string | Value in the specified column as a string.|

**Example**
  ```js
  const name = resultSet.getString(resultSet.getColumnIndex("NAME"))
  ```


### getLong

getLong(columnIndex: number): number

Obtains the value in the specified column in the current row as a Long.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | columnIndex | number | Yes| Index of the specified column, starting from 0.|

**Return value**
  | Type| Description|
  | -------- | -------- |
  | number | Value in the specified column as a Long.|

**Example**
  ```js
  const age = resultSet.getLong(resultSet.getColumnIndex("AGE"))
  ```


### getDouble

getDouble(columnIndex: number): number

Obtains the value in the specified column in the current row as a double.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | columnIndex | number | Yes| Index of the specified column, starting from 0.|

**Return value**
  | Type| Description|
  | -------- | -------- |
  | number | Value in the specified column as a double.|

**Example**
  ```js
  const salary = resultSet.getDouble(resultSet.getColumnIndex("SALARY"))
  ```


### isColumnNull

isColumnNull(columnIndex: number): boolean

Checks whether the value in the specified column of the current row is null.

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

**Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | columnIndex | number | Yes| Index of the specified column, starting from 0.|

**Return value**
  | Type| Description|
  | -------- | -------- |
  | boolean | Returns **true** if the value is null; returns **false** otherwise.|

**Example**
  ```js
  const isColumnNull = resultSet.isColumnNull(resultSet.getColumnIndex("CODES"))
  ```


### close

close(): void

Closes this result set.

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

**Example**
  ```js
  let predicatesClose = new dataRdb.RdbPredicates("EMPLOYEE")
  let promiseClose = rdbStore.query(predicatesClose, ["ID", "NAME", "AGE", "SALARY", "CODES"])
  promiseClose.then((resultSet) {
      resultSet.close()
  }).catch((err) => {
      console.log('Failed to close resultset')
  })
  ```