MySQL Trigger: Delete From Table AFTER DELETE

Question

Scope: Two tables. When a new patron is created, they have some information about them stored into a 2nd table (This was done using a trigger as well, it works as expected)

Answer 1

I think there is an error in the trigger code. As you want to delete all rows with the deleted patron ID, you have to use old.id (Otherwise it would delete other IDs)

Try this as the new trigger:

CREATE TRIGGER log_patron_delete AFTER DELETE on patrons
FOR EACH ROW
BEGIN
DELETE FROM patron_info
    WHERE patron_info.pid = old.id;
END

Dont forget the ";" on the delete query. Also if you are entering the TRIGGER code in the console window, make use of the delimiters also.

Answer 2

Why not set ON CASCADE DELETE on Foreign Key patron_info.pid?

Answer 3

create trigger doct_trigger
after delete on doctor
for each row
delete from patient where patient.PrimaryDoctor_SSN=doctor.SSN ;