Use Global Temp Table to overcome Mutating Trigger issue

Question

Hello all. I need to delete a line in a table, and thought I would get around the mutating trigger issue by creating a GTB table. I created 2 different triggers. One is a Row level trigger, the other a Statement level trigger.
The first trigger gathers the information I need to identify the line I want to delete. This is:
CREATE OR REPLACE TRIGGER Requisition_Capture
AFTER UPDATE OF Delivery_Code on Supply_Items
FOR EACH ROW
BEGIN
  IF :NEW.Delivery_Code = '#' THEN
    INSERT INTO Requisition_Storage
      (Req_Code)
    VALUES
      (:NEW.Requisition_Code);
  END IF;
END;And the second trigger deletes the line:
CREATE OR REPLACE TRIGGER SUPPLY_ITEM_RESET
AFTER INSERT ON Requisition_Storage
DECLARE
BEGIN
  DELETE FROM Supply_Items r
   WHERE r.Requisition_Code =
         (SELECT t.Req_Code
            FROM Requisition_Storage t, Supply_Items s
           WHERE t.Req_Code = s.Requisition_Code)
     AND r.Order_Qty = 0;
END;The GTB is as follows stores the information I need to delete the line.:
-- Create table
create global temporary table REQUISITION_STORAGE
  req_code VARCHAR2(20)
on commit delete rows;When the column Delivery_Code is updated in the Supply_Item table, and the value is reset to '#', I want to capture the Requisition_Code in the GTB, so I can run the statement level trigger and delete the reset row. However, I still have a mutating error problem. What am I missing?

Answer 1

The statement level trigger would need to be an AFTER UPDATE OF Supply_Items for this to work around the mutating trigger issue. You need to ensure that your UPDATE has finished updating all the rows that it is going to update before your statement-level trigger runs.
As has been pointed out, however, the desire to work around a mutating trigger error almost always indicates that you have a data model problem. And you're almost always better served by fixing the data model than working around the error.
Justin