Description Fires during Execute Query or Count Query processing, just before Form Builder constructs and issues the SELECT statement to identify rows that match the query criteria. Definition Level form or block Legal Commands SELECT statements, unrestricted built-ins Enter Query Mode no
Usage Notes Use a Pre-Query trigger to modify the example record that determines which rows will be identified by the query. On Failure The query is canceled. If the operator or the application had placed the form in Enter Query mode, the form remains in Enter Query mode. Fires In COUNT_QUERY EXECUTE_QUERY Open the Query Prepare the Query See Process Flowcharts Pre-Query trigger examples Example This example validates or modifies query criteria for a database block query. BEGIN /* ** Set the ORDER BY clause for the current block ** being queried, based on a radio group ** called ’Sort_Column’ in a control block named ** ’Switches’. The Radio Group has three buttons ** with character values giving the names of ** three different columns in the table this ** block is based on: ** ** SAL ** MGR,ENAME ** ENAME */ Set_Block_Property(’EMP’,ORDER_BY, :Switches.Sort_Column); /* ** Make sure the user has given one of the two ** Columns which we have indexed in their search ** criteria, otherwise fail the query with a helpful ** message */ IF :Employee.Ename IS NULL AND :Employee.Mgr IS NULL THEN Message(’Supply Employee Name and/or Manager Id ’|| ’for Query.’); RAISE Form_trigger_Failure; END IF; /* ** Change the default where clause to either show "Current ** Employees Only" or "Terminated Employees" based on the ** setting of a check box named ’Show_Term’ in a control ** block named ’Switches’. */ IF Check box_Checked(’Switches.Show_Term’) THEN Set_Block_Property(’EMP’,DEFAULT_WHERE,’TERM_DATE IS NOT NULL’); ELSE Set_Block_Property(’EMP’,DEFAULT_WHERE,’TERM_DATE IS NULL’); END IF; END;
