在触发器内使用select语句

Question

So i have learned somhing abou triggers in mysql..While i as using selct statement inside the trigger it throws me error ..So after some research i have seen that using select statement and inserting into a variable can be done in trigger..So the code which i have used is

CREATE TRIGGER ins_sum AFTER UPDATE ON foo
FOR EACH ROW

declare some int;

select a from foo into some;


UPDATE foo SET a = 3 WHERE b = 1;

But it throws me error like Schema Creation Failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'declare some int'

Why is it like this ??..Any help would be apreciated..Thanx

Answer 1

I presume that the UPDATE foo is not part of the trigger as it wouldn't work within a trigger on UPDATE foo.

DELIMITER //
CREATE TRIGGER ins_sum AFTER UPDATE ON foo
FOR EACH ROW
BEGIN
 declare some int;

 select NEW.a from foo into some;
END
//

DELIMITER ;