mysql - 带参数的MySQL函数出错

Question

我的 MySQL 函数有 2 个参数，即 user_id 和 post_id

这是我的功能:

CREATE FUNCTION isliked(pid INT, uid INT)
RETURN TABLE
AS
RETURN (EXISTS (SELECT 1 FROM likedata ld WHERE post_id = pid AND user_id = uid
       )) as is_liked
END

我试着用下面的查询调用它:

SELECT posts.id, posts.title, isliked(111,123)
FROM posts

它返回以下错误:

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 'RETURN TABLE
AS
RETURN (EXISTS (SELECT 1 FROM likedata ld WHERE post_id = pid AN' at line 2

应该是这样的返回结果http://sqlfiddle.com/#!9/91040/5 我是 sql 新手，任何帮助都会很棒，提前致谢

Answer 1

如果您希望函数返回 bool 值，请使用:

CREATE FUNCTION isliked(pid INT, uid INT)
RETURNS BIT
   RETURN ( EXISTS ( SELECT 1 FROM likedata ld WHERE post_id = pid AND user_id = uid ) )