Fires during Execute Query or Count Query processing, just before Oracle Forms constructs and issues the SELECT statement to identify rows that match the query criteria.
Definition Level form or block
SELECT statements, unrestricted Built-ins
Enter Query Mode no
Use a Pre-Query trigger to modify the example record that determines which rows will be identified by the query.
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.
COUNT_QUERY
EXECUTE_QUERY
Open the Query
Prepare the Query
This example validates or modifies query criteria for a database block query.
/*
** 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
*/
BEGIN
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;
About controlling queries with Pre-Query and Post-Query triggers