我有存储过程:
BEGIN
SELECT @id_for_del := ful.social_id
FROM facebook_users_likes ful
where
(select count(*) from facebook_users fu where fu.social_id = ful.social_id) = 0;
IF NOT @id_for_del IS NULL
THEN
DELETE from facebook_users_likes WHERE social_id = @id_for_del;
END IF;
END
选择会返回46 000行,但每个执行存储过程只删除一行。 那么,如何一次删除所有46 000行?
答案 0 :(得分:1)
以下是select
到delete
:
DELETE FROM facebook_users_likes ful
WHERE (select count(*) from facebook_users fu where fu.social_id = ful.social_id) = 0;
在此上下文中使用not exists
更有效:
DELETE FROM facebook_users_likes ful
WHERE NOT EXISTS (select 1 from facebook_users fu where fu.social_id = ful.social_id);
如果您在facebook_users(social_id)
上有索引,则尤其如此。