Whenever we commit after entering data in Oracle Forms, many triggers fires during this event and also Pre-Update and Pre-Insert triggers fires just before inserting or updating the record into table. We can write Pre-Update and Pre-Insert triggers on particular block to just allow the process or to stop the process by using "Raise Form_Trigger_Failure" command, the following are the some examples:
Suppose you have a data block and there is a field which need to be validate just before inserting the record, then you must write the Pre-Insert trigger for this purpose, below is an example:
Declare v_avl_qty number; Begin   Select avl_qty into v_avl_qty    From stock_inhand   Where Item_Code = :Block1.item_code; if v_avl_qty < :Block1.qty_issued then Raise Form_Trigger_Failure; --- Execution stopped... end if; --- Else insertion will take place... End;
And now I am giving you another example, suppose there is a field which need to be assigned from database just before the updation of the record, then you must write a Pre-Update trigger for this purpose, below is an example:
Declare   v_value varchar2(10); Begin   Select a_value into v_value    From a_table   Where b_value = :Block1.b_value; --- Assign this value to block item :Block1.a_value := v_value; --- you can assign any others value to any field just before updation or insertion like: :Block1.create_date := Sysdate; Exception  when others then    --- After any error or no data found you still want to continue then you can use only Null; statement    Null;    --- and any other value to any field you can still assign :Block1.create_date := Sysdate; End;
See also:Â Pre-Update and Pre-Insert Trigger Examples For Oracle Forms