Fire a trigger after the update of specific columns in MySQL

Question

In MySQL, I want to fire a trigger after the update of specific columns.

I know how to do it in Oracle and DB2:

CREATE  TRIGGER  myTrigger
A         


        

Answer 1

You can't specify only to fire on specific column changes. But for a record change on a table you can do

delimiter |
CREATE  TRIGGER  myTrigger AFTER UPDATE ON myTable
FOR EACH ROW
BEGIN
   ...
END
|
delimiter ;

In your trigger you can refer to old and new content of a column like this

if NEW.column1 <> OLD.column1 ...