@ohos.data.dataAbility (DataAbility Predicates)

The DataAbility module provides APIs to create predicates for querying data from relational database (RDB) stores.

NOTE

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 { dataAbility } from '@kit.ArkData';

dataAbility.createRdbPredicates

createRdbPredicates(name: string, dataAbilityPredicates: DataAbilityPredicates): rdb.RdbPredicates

Creates an RdbPredicates object with a table name and DataAbilityPredicates object.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  let dataAbilityPredicates = new dataAbility.DataAbilityPredicates()
  dataAbilityPredicates.equalTo("NAME", "Rose")
  // EMPLOYEE is a table created in an RDB store.
  let predicates = dataAbility.createRdbPredicates("EMPLOYEE", dataAbilityPredicates)

DataAbilityPredicates

Provides APIs for creating diverse query conditions.

Initialization

  let dataAbilityPredicates = new dataAbility.DataAbilityPredicates()

equalTo

equalTo(field: string, value: ValueType): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are equal to the given value.

This API is similar to the SQL equal to (=) operator.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.equalTo("NAME", "lisi")

notEqualTo

notEqualTo(field: string, value: ValueType): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are not equal to the given value.

This API is similar to the SQL not equal (!=) operator.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.notEqualTo("NAME", "lisi")

beginWrap

beginWrap(): DataAbilityPredicates

Creates a DataAbilityPredicates object to add a left parenthesis. This API is similar to “(” in an SQL statement and must be used with endWrap.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Return value

Example

  dataAbilityPredicates.equalTo("NAME", "lisi")
      .beginWrap()
      .equalTo("AGE", 18)
      .or()
      .equalTo("SALARY", 200.5)
      .endWrap()

endWrap

endWrap(): DataAbilityPredicates

Creates a DataAbilityPredicates object to add a right parenthesis. This API is similar to “)” in an SQL statement and must be used with beginWrap.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Return value

Example

  dataAbilityPredicates.equalTo("NAME", "lisi")
      .beginWrap()
      .equalTo("AGE", 18)
      .or()
      .equalTo("SALARY", 200.5)
      .endWrap()

or

or(): DataAbilityPredicates

Creates a DataAbilityPredicates object to add the OR condition.

This API is similar to the SQL or operator.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Return value

Example

  dataAbilityPredicates.equalTo("NAME", "Lisa")
      .or()
      .equalTo("NAME", "Rose")

and

and(): DataAbilityPredicates

Creates a DataAbilityPredicates object to add the AND condition.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Return value

Example

  dataAbilityPredicates.equalTo("NAME", "Lisa")
      .and()
      .equalTo("SALARY", 200.5)

contains

contains(field: string, value: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that contain the given value.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.contains("NAME", "os")

beginsWith

beginsWith(field: string, value: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that begin with the given value.

This API is similar to the percent sign (%) in SQL statements.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.beginsWith("NAME", "os")

endsWith

endsWith(field: string, value: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that end with the given value.

This API is similar to the percent sign (%) in SQL statements.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.endsWith("NAME", "se")

isNull

isNull(field: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are null.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.isNull("NAME")

isNotNull

isNotNull(field: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are not null.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.isNotNull("NAME")

like

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

Creates a DataAbilityPredicates object to search for the records in the specified column that are similar to the given value.

This API is similar to the SQL like statement.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.like("NAME", "%os%")

glob

glob(field: string, value: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that match the given string. Different from like, the input parameters of this API are case-sensitive.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.glob("NAME", "?h*g")

  // Only the records whose value is "Lisa" in the "name" column are matched.
  dataAbilityPredicates.glob("NAME", "Lisa")

  // Only the records whose value is "lisa" in the "name" column are matched.
  dataAbilityPredicates.glob("NAME", "lisa")

between

between(field: string, low: ValueType, high: ValueType): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are within the given range.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.between("AGE", 10, 50)

notBetween

notBetween(field: string, low: ValueType, high: ValueType): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are out of the given range.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.notBetween("AGE", 10, 50)

greaterThan

greaterThan(field: string, value: ValueType): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are greater than the given value.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.greaterThan("AGE", 18)

lessThan

lessThan(field: string, value: ValueType): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are less than the given value.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.lessThan("AGE", 20)

greaterThanOrEqualTo

greaterThanOrEqualTo(field: string, value: ValueType): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are greater than or equal to the given value.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.greaterThanOrEqualTo("AGE", 18)

lessThanOrEqualTo

lessThanOrEqualTo(field: string, value: ValueType): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are less than or equal to the given value.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.lessThanOrEqualTo("AGE", 20)

orderByAsc

orderByAsc(field: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to sort the records in the specified column in ascending order. When there are multiple orderByAscs, the first orderByAsc used has the highest priority.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  // Sort data by name first; for the records with the same name, sort them by age; for the records with the same name and age, sort them by salary in ascending order.
  dataAbilityPredicates.orderByAsc("NAME").orderByAsc("AGE").orderByAsc("SALARY")

orderByDesc

orderByDesc(field: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to sort the records in the specified column in descending order. When there are multiple orderByDescs, the first orderByDesc used has the highest priority.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  // Sort the data by age first. For the data records with the same age, sort them by salary.
  dataAbilityPredicates.orderByDesc("AGE").orderByDesc("SALARY")

distinct

distinct(): DataAbilityPredicates

Creates a DataAbilityPredicates object to filter out duplicate records.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Return value

Example

  dataAbilityPredicates.equalTo("NAME", "Rose").distinct()

limitAs

limitAs(value: number): DataAbilityPredicates

Creates a DataAbilityPredicates object to limit the number of records.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.equalTo("NAME", "Rose").limitAs(3)

offsetAs

offsetAs(rowOffset: number): DataAbilityPredicates

Creates a DataAbilityPredicates object to set the start position of the query result. This API must be used together with limitAs. Otherwise, no result will be returned. To query all rows after the specified offset, pass in -1 in limitAs.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  // Display the three data records following the first three records.
  dataAbilityPredicates.equalTo("NAME", "Rose").offsetAs(3).limitAs(3)

groupBy

groupBy(fields: Array<string>): DataAbilityPredicates

Creates a DataAbilityPredicates object to group the query results based on the specified columns.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.groupBy(["AGE", "NAME"])

indexedBy

indexedBy(field: string): DataAbilityPredicates

Creates a DataAbilityPredicates object to specify the index column. Before calling this API, you need to create an index column.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  import { dataAbility, relationalStore } from '@kit.ArkData';

  let context = getContext(this);

  const STORE_CONFIG : relationalStore.StoreConfig = {
      name: 'RdbTest.db', // Database file name.
      securityLevel: relationalStore.SecurityLevel.S3,
  };
  // Table structure: EMPLOYEE (NAME, AGE, SALARY, CODES)
  const SQL_CREATE_TABLE = 'CREATE TABLE IF NOT EXISTS EMPLOYEE (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT NOT NULL, AGE INTEGER, SALARY REAL, CODES BLOB)'; // SQL statement for creating a data table.
  relationalStore.getRdbStore(context, STORE_CONFIG, async (err, store) => {
    if (err) {
      console.error(`Failed to get RdbStore. Code:${err.code}, message:${err.message}`);
      return;
    }
    console.info('Succeeded in getting RdbStore.');


    await store.executeSql(SQL_CREATE_TABLE); // Create a data table.


    // Create an index.
    const SQL_CREATE_INDEX = 'CREATE INDEX SALARY_INDEX ON EMPLOYEE(SALARY)'
    await store.executeSql(SQL_CREATE_INDEX);
    // ...

    let dataAbilityPredicates = new dataAbility.DataAbilityPredicates()
    dataAbilityPredicates.indexedBy("SALARY_INDEX")

    //  ...
  })

in

in(field: string, value: Array<ValueType>): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are in the given range.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.in("AGE", [18, 20])

notIn

notIn(field: string, value: Array<ValueType>): DataAbilityPredicates

Creates a DataAbilityPredicates object to search for the records in the specified column that are out of the given range.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

Parameters

Return value

Example

  dataAbilityPredicates.notIn("NAME", ["Lisa", "Rose"])

ValueType

type ValueType = number|string|boolean

Defines the value types.

System capability: SystemCapability.DistributedDataManager.DataShare.Core

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