Question

I have a database where the customer wants run an DELETE statement. But on database side, the record should be just hidden instead of deleted.

Can i use a BEFORE DELETE TRIGGER to change the visiblity flag to false instead of deleting the record?

Answer 1

I think the only way to do this in MySQL (as Alex Monthy hinted, is that really where this logic belongs?) is to use an after delete trigger that re-inserts the record with the visibility flag set to false:

CREATE TRIGGER foo AFTER DELETE ON my_table FOR EACH ROW
  INSERT INTO my_table (visibility,     colA,     colB,     colC)
                VALUES (     false, OLD.colA, OLD.colB, OLD.colC);

You can abort the delete operation from a before trigger (just make the trigger raise an error, e.g. call an non-existent procedure), but that won’t enable you to update the visibility flag as desired.