Greg Allard (10/08): OLD and NEW are used on...

How To Use Triggers to Track Changes in MySQL

on Code Spatter from 35 weeks ago

OLD and NEW are used on UPDATE triggers. OLD.col_names will access the data that is in the row of the database before the UPDATE query runs and NEW.col_names will access the data that the row will be updated to.

IF OLD.first_name != NEW.first_name

That checks if the UPDATE query is changing the information for first_name.