Link the two Data Source by using Query...

static void Query(Args _args)
{
    Query                              q;
    QueryRun                        qr;
    QueryBuildDataSource    custDataSource,transDataSource;
    QueryBuildRange            qbr;
    QueryBuildLink               qbl;
    CustTable                       custTable;
    CustTrans                       custTrans;
    ;
    q = new Query();
  
    //Adding the parent DataSource
    custDataSource  = q.addDataSource(tablenum(CustTable));
  
    //Adding the range
    qbr                    = custDataSource.addRange(fieldnum(CustTable,AccountNum));
    custDataSource.addSortField(fieldnum(CustTable,AccountNum));
  
    transDataSource = custDataSource.addDataSource(tablenum(custTrans));

    //Adding the Inner join for the two tables CustTable and CustTrans
    transDataSource.joinMode(JoinMode::InnerJoin);
  
    //Adding the relation for the two tables
    //If the realtion doesn't exists
    qbl             =
    transDataSource.addLink(fieldnum(CustTable,AccountNum),fieldnum(CustTrans,Accountnum));
  
    //If the relation already exists for the two tables in the table level...
    //Then we can use the following one...
    transDataSource.relations(true);

    qr = new QueryRun(q);
    while(qr.next())
    {
        //Logic to print the data from query..
    }
}