Execute a trigger on the same table if updating

Question

I need to execute a trigger that includes an UPDATE statement on the same table.

I have tried this code. If I check the table, the row is updated, but I get an error message:

Can't update table 'Orders' in stored function/trigger because it is already used by statement which invoked this stored function/trigger

DROP TRIGGER IF EXISTS UpdateTotal;

DELIMITER |

CREATE TRIGGER UpdateTotal BEFORE UPDATE ON Orders
FOR EACH ROW 
BEGIN
  UPDATE Orders P1
    SET NEW.order_total = NEW.order_total + 3.02
    WHERE order_id IN (SELECT * FROM (SELECT MAX(order_id) FROM Orders) P2);
END

|

DELIMITER ;

Answer 1

you can't do all this in a trigger. According to the documentation :

Within a stored function or trigger, it is not permitted to modify a table that is already being used (for reading or writing) by the statement that invoked the function or trigger.

explain more about requirement and table structure.