MySQL IF Statement issue in a Trigger - mysql

Question

So I am trying to create trigger that will only execute when a specific column within a table is updated. The table in question is track the column in question is track.track_hits. What I want to do is if that value changes then it inserts a value into a table called play_log. The insert should be the track_id from track and a timestamp.
The code I have done so far is below but it doesn't work, how can it be fixed?
CREATE TRIGGER pi_play AFTER UPDATE ON track
FOR EACH ROW
BEGIN
if :new.track_hits != :old.track_hits
then
INSERT INTO play_log (track_id,access_time)
VALUES (NEW.track_id, NOW())
end if;
END;

Answer 1

NEW and OLD do not need : in front. Also, when creating triggers, you may need to change the delimiter. If you don't change the delimiter, your create trigger statement may be terminated early.
Here's how I would do it:
delimiter |
create trigger pi_play after update on track
for each row
begin
if new.track_hits != old.track_hits then
insert into play_log(track_id, access_time) values (new.track_id, now());
end if;
end|
delimiter ;
Here's the fiddle showing it in action: http://sqlfiddle.com/#!2/3d99d/1 Notice that I changed the delimiter in the schema window to | instead of the default ;. Since SQL uses JDBC and JDBC doesn't take the command DELIMITER, I chose the delimiter.