Axapta queries Fact

The query object model contains classes to define and run a query. These objects are used to define the query data source, the fields returned, record ranges and relations to child data sources. The following illustration shows the object model.

 

The query components shown in the previous figure are system classes. The query classes are more visible when you create a dynamic query in code, but they are also used behind the scenes when you create a static query in the AOT.

System class	Description
QueryRun	Executes the query and fetches the data.
Query	The top level of the query definition. This class holds some properties itself and has one or more related data sources.
QueryBuildDataSource	Defines access to a single data source in the query. If more than one data source exists at the same level in a query, they result in separate SQL statements that are executed sequentially. If one data source exists as a child of another data source, a join is created between the two data sources.
QueryBuildFieldList	Defines which fields are returned from the database. The default is that the field list is dynamic, which returns all fields from the data source table, map, or view. Each data source has only one QueryBuildFieldList object, which contains information on all selected fields. It's possible to specify aggregate functions like SUM, COUNT, and AVG on the field list object.
QueryBuildRange	Defines a subset of records returned based on a single field. A range is translated into a WHERE clause in the query SQL statement. If more than one field is used to limit the query (WHERE clause), the data source will contain more than one range.
QueryBuildDynalink	Contains information regarding a relation (limitation) to an external record. When the query is run, this information is converted to additional entries in the WHERE clause of the query SQL statement. Can only exist on the parent data source of a query. The function is used by forms, when two data sources are synchronized. Then the child data source will contain a dynalink or dynalinks to the parent data source. The function is used even if the two data sources are placed in two different forms but are still synchronized.
QueryBuildLink	Specifies the relation between the two data sources in the join. Can only exist on a child data source.

[Source for above text: Microsoft Dyanmics AX 4.0 Developer Guide]

Below is a job that can illustrate usage different query framework classes

static void queryCreation(Args _args)
{
    Query                   query = new Query('MyQuery');
    QueryBuildDataSource    custTableQBDS, custTransQBDS;
    QueryBuildRange         qbr1, qbr2;
    QueryBuildFieldList     qbFl, qbF2, qbF3;
    QueryBuildLink          qbl;
    QueryBuildDynalink      qbdl;
    QueryRun                qr;

    CustTable               custTable;
    CustTrans               custTrans;
    LedgerTrans             ledgerTrans;
    ;

    custTableQBDS = query.addDataSource(tablenum(custTable));

    //This will enable you to add the fields you like
    //If dynamics is yes all the fields will be automatically added
    custTableQBDS.fields().dynamic(NoYes::No);
    qbFl = custTableQBDS.fields().addField(fieldNum(CustTable, AccountNum));
    qbF2 = custTableQBDS.fields().addField(fieldNum(CustTable, InvoiceAccount));
    qbF3 = custTableQBDS.fields().addField(fieldNum(CustTable, CustGroup));

    //Adding Ranges
    qbr1 = query.dataSourceTable(tableNum(CustTable)).addRange(fieldNum(CustTable, AccountNum));
    qbr2 = query.dataSourceTable(tableNum(CustTable)).addRange(fieldNum(CustTable, InvoiceAccount));
    qbr1.value(SysQuery::value('4011'));
    qbr2.value(SysQuery::value('4010'));

    //Add child data source to main datasource
    custTransQBDS = custTableQBDS.addDataSource(tableNum(CustTrans));

    //Two ways to add relation
    //First - This may not work in all the scenarios
    custTransQBDS.relations(true);

    //Second - QueryBuildLink
    qbl = custTransQBDS.addLink(fieldNum(CustTable, AccountNum), fieldNum(CustTrans, AccountNum));

    SetPrefix ('Queries');
    setPrefix ('Dynalinks');

    qr = new QueryRun(query);
    setPrefix ('Without');
    while (qr.next())
    {
        if (qr.changed(tableNum(CustTable)))
        {
            custTable = qr.get(tableNum(CustTable));
        }
        setPrefix ('Customer - ' + custTable.AccountNum);

        if (qr.changed(tableNum(CustTrans)))
        {
            custTrans = qr.get(tableNum(CustTrans));
            info(custTrans.Voucher);
        }
    }

    //Dynalink test so run the loop after dynamically linking with a table    select firstonly ledgerTrans where ledgerTrans.Voucher == 'US_800006' &&
            ledgerTrans.AccountNum == '130100';

    custTransQBDS.addDynalink(fieldNum(CustTrans, Voucher), ledgerTrans, fieldNum(LedgerTrans, Voucher));
    custTransQBDS.addDynalink(fieldNum(CustTrans, TransDate), ledgerTrans, fieldNum(LedgerTrans, TransDate));

    qr = new QueryRun(query);

    setPrefix('Dynalinks');
    setPrefix ('With');
    while (qr.next())
    {
        if (qr.changed(tableNum(CustTable)))
        {
            custTable = qr.get(tableNum(CustTable));
        }
        setPrefix ('Customer - ' + custTable.AccountNum);

        if (qr.changed(tableNum(CustTrans)))
        {
            custTrans = qr.get(tableNum(CustTrans));
            info(custTrans.Voucher);
        }
    }
}