ZCQL

ZCQL is Catalyst’s own query language that enables you to perform data creation, retrieval, and modification operations in the Data Store. It supports queries with built-in functions, SQL Join clauses, and other statements and conditions.

Execute a ZCQL Query

Before you execute a ZCQL query to fetch the required data set, you must construct the query to pass it to the execute() method. You can learn about the ZCQL syntax from the ZCQL help page.

You must pass an instance of ZCatalystSelectQuery to the execute() method, as shown in the code syntax of a ZCQL query execution below.

The <DATA_STORE_INSTANCE> used here is the instance defined in the Data Store Instance page.

    

        
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         ZCatalystApp.getInstance().getDataStoreInstance().execute(
    selectQuery: ZCatalystSelectQuery,
    success: (List<Map<String, Map<String, Any?>>>) → Unit,
    failure: ((ZCatalystException) → Unit)?
): ZCatalystRequest<ZCatalystResponse<List<Map<String, Any?>>>>>?

    

Parameters:

• selectQuery: The instance of the type ZCatalystSelectQuery to be passed

You can create a selectQuery instance for ZCatalystSelectQuery for the statements supported by ZCQL, in the following way:

    

        
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         ZCatalystSelectQuery.Builder()
   .select(columns: Set<Column>): ZCatalystSelectQuery.Builder
   .selectAll(): ZCatalystSelectQuery.Builder
   .where(column: String, comparator: ZCatalystUtil.Comparator, value: String): ZCatalystSelectQuery.Builder
   .from(tableName: String): ZCatalystSelectQuery.Builder
   .and(column: String, comparator: ZCatalystUtil.Comparator, value: String): ZCatalystSelectQuery.Builder
   .groupBy(columns: Set<Column>): ZCatalystSelectQuery.Builder
   .orderBy(columns: Set<Column>, sortOrder: ZCatalystUtil.SortOrder): ZCatalystSelectQuery.Builder
   .innerJoin(tableName: String): ZCatalystSelectQuery.Builder
   .leftJoin(tableName: String): ZCatalystSelectQuery.Builder
   .on(joinColumn1: String, comparator: ZCatalystUtil.Comparator, joinColumn2: String): ZCatalystSelectQuery.Builder
   .or(column: String, comparator: ZCatalystUtil.Comparator, value: String): ZCatalystSelectQuery.Builder
   .limit(offset: Int, value: Int?): ZCatalystSelectQuery.Builder
   .build(): ZCatalystSelectQuery

    

A sample code snippet of a ZCQL query execution is shown below:

    

        
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         val query = ZCatalystSelectQuery.Builder()
    .selectAll()
    .from("EmployeeDetails") //Replace this with your table name
    .where("Location", ZCatalystUtil.Comparator.EQUAL_TO, "Austin")
    .and("Department", ZCatalystUtil.Comparator.EQUAL_TO, "Marketing")
    .or("isActive", ZCatalystUtil.Comparator.EQUAL_TO, "true")
    .limit(5)
    .build()

ZCatalystApp.getInstance().getDataStoreInstance().execute(query,
    {
        println("Query executed successfully. $it")
    },
    {
        exception -> println("Exception occured $exception")
    })