Question

I have a table with 3 fields, one of them is “status”.
status is an ENUM with possible content ‘a’, ‘b’ or ‘c’.

I need to find a way to deny any update on all rows having “status” = ‘b’ not even the root user should be allowed to update these rows. So its like making this row “final”.
Update should be allowed if status = a or status = c.

Is there any way to do this?
Thanks!

Answer 1

You can use this trigger –

DELIMITER $$

CREATE TRIGGER trigger1
  BEFORE UPDATE
  ON table1
  FOR EACH ROW
BEGIN
  IF OLD.status = 'b' THEN
    SIGNAL SQLSTATE '02000' SET MESSAGE_TEXT = 'Cannot update value';
  END IF;
END
$$

DELIMITER ;

If you know the bane of toot user and want to allow him to update, then you can use this condition –

...
IF CURRENT_USER() <> 'root@localhost' AND OLD.status = 'b' THEN
  SIGNAL SQLSTATE '02000' SET MESSAGE_TEXT = 'Cannot update value';
END IF;
...