MySQL trigger to update a field to the value of id

Question

I would like to have a trigger to perform following operation for inserted records:

 # pseudocode
 if new.group_id is null
    set new.group_id = new.id
 els         


        

Answer 1

This works for me

DELIMITER $$
CREATE TRIGGER `myTriggerNameHere`
BEFORE INSERT ON `table` FOR EACH ROW
BEGIN
    SET NEW.group_id = IF(NEW.group_id IS NULL, LAST_INSERT_ID()+1, NEW.group_id);
END;
$$
DELIMITER ;