Query -- Exists Join

Combine records from one table whenever a value exists in a common field in another table.

Display inventory items the providing vendor who has been blocked.
    InventTable inventTable;
    VendTable vendTable;
    ;

    ttsbegin;

    while select forupdate inventTable
     exists join vendTable
      where vendTable.AccountNum == inventTable.PrimaryVendorId &&
vendTable.Blocked == CustVendorBlocked::All
    {
        inventTable.PrimaryVendorId ="";
        inventTable.update();
    }
    ttscommit;

Display only those customers which have at least one sales order in sales table. 

Query                   query;

QueryBuildDatasource    datasource,SalesDataSource,CustomerDataSource;

QueryRun   queryrun;

CustTable custtable;

SalesTable salesTable; 

query = new Query();

CustomerDataSource  = query.addDataSource(tableNum(CustTable ));

SalesDataSource  = CustomerDataSource.addDataSource(tableNum(SalesTable ));

SalesDataSource.joinMode(JoinMode::ExistsJoin   );

SalesDataSource.relations(false);

SalesDataSource.addLink(fieldNum(CustTable, AccountNum),

fieldNum(SalesTable  , CustAccount ));

queryrun = new QueryRun(query);

while(queryRun.next())

{

custtable = queryRun.get(tablenum(CustTable ));

Info(custtable.AccountNum);

}