An Example of Pre-Query and Post-Query Triggers in Oracle Forms With Using Display_Item to Highlight Dynamically

Example is given for Pre-Query and Post-Query triggers in Oracle Forms, with using Display_Itembuilt-in in Post-Query triggers to highlight fields dynamically.

 

This is the screen shot below for this example:

 

You can also download this form from the following link: Query.fmb

 

The example is based on HR schema departments table. In this example Department No. and Execute Query push button is in upper block named "Ctrl" block and below block is the departments block. User will be asked to enter department no. in above block and then to click on Execute Query button to filter the records below. The filtration is handled in Pre-Query trigger and after execution of query the Manager Name and Salary will be populated in Post-Query trigger by dynamically highlighting the Manager Name using Display_Item built-in.

 

The following code written in Pre-Query trigger of Departments block to filter the records:

 

if :ctrl.deptno is not null then

  -- set default_where property of the block to the ctrl block item to filter the records before query

  set_block_property('departments', default_where, 'department_id = :ctrl.deptno');

end if;

The following code written in Post-Query trigger of Departments block to populate non-database item fields and dynamically highlighting the Manager Name field:

 

begin
 select first_name, salary into :departments.empname, :departments.sal
   from hr.employees where employee_id = :departments.manager_id;
   -- highlight as per your criteria
   if :sal >= 10000 then
                  -- create highlight visual attribute with color of your choice to highlight
      display_item('departments.empname', 'highlight');
   else
                 -- create default1 visual attribute to restore to normal view
      display_item('departments.empname', 'default1');
   end if;
exception
 when others then
   null;
end;

The following code written in When-Button-Pressed trigger of Execute Query push button in Ctrl block to execute query in Departments block:

 

go_block('departments');
set_block_property('departments', default_where, '');
execute_query;

See also: Oracle Forms Recipes Define Custom Filter Using Pre-Query Trigger