Question

SELECT *, 
IF(users_posts.uid IN (SELECT puid FROM post_ups WHERE  post_ups.uid = UID LIMIT 400 ) AND users_posts.uid  <> UID ,10,0)
    FROM users_posts

我收到此错误

这个版本的MySQL还没有支持＆＃39; LIMIT＆amp; IN / ALL / ANY / SOME 子查询＆＃39;

我如何在子查询上使用限制，并且我可以将其转换为连接语句，并且这个查询对性能有利吗？理论上这可以运行+百万重新编码？

更新这个代码会产生与上面相同的结果吗？

SELECT *,IF(ups.puid = t1.uid,10,0)
    FROM users_posts t1
    LEFT JOIN (SELECT puid FROM post_ups WHERE  post_ups.uid = 135 ORDER BY `created_date` DESC LIMIT 400 ) AS ups ON ups.puid = t1.uid  AND t1.uid  <> 135

Answer 1

您可以通过

执行此操作

`SELECT *, 
IF(users_posts.uid IN (select * from (SELECT puid FROM post_ups WHERE  post_ups.uid = UID LIMIT 400) tmp_tbl ) AND users_posts.uid  <> UID ,10,0)
    FROM users_posts`

或代替LEFT JOIN使用INNER JOIN。

SELECT *,IF(ups.puid = t1.uid,10,0)
FROM users_posts t1 INNER JOIN (SELECT puid FROM post_ups WHERE  post_ups.uid = 135 ORDER BY `created_date` DESC LIMIT 400 ) AS ups ON ups.puid = t1.uid  AND t1.uid  <> 135

MySQL还没有支持LIMIT＆amp; IN / ALL / ANY / SOME

1 个答案: