帮助创建相当复杂的sql语句

大家好，我真的不知道如何用谷歌搜索的形式来描述这一点，所以我决定来这里看看你们是否能帮上忙。基本上，我想知道如何将以下伪sql转换为实际的mysql查询：

Select one random row 
  from `posts` 
 where (the user's id, which is supplied by the script) is not found in the `votes` table 
        with a post id of (the selected post's id).

非常感谢您的帮助。

类似这样的内容：

SELECT *
FROM Posts
WHERE Posts.ID NOT IN (
    SELECT Votes.PostID FROM Votes WHERE Votes.UserID=@UserID
)
ORDER BY Rand()
LIMIT 1

根据我的经验，联接比subselect快得多，尤其是与

NOT in

子句

NOT in组合使用时

---

左连接/左连接为空

---

不存在

---

总结

---

不建议使用“

ORDER BY RAND（）”

，因为它不会随着数据量的增加而扩展（）

---

notin

和

LEFT JOIN/IS NULL

在MySQL上是等价的：哇，我不知道。。。我想这是一个主观性的问题：-）。谢谢你指出这一点！对于MS SQL（至少到2005年）通常为true，对于Oracle（至少到10g）通常为false，对于MySQL通常相当；）

SELECT p.* 
FROM `posts`
LEFT JOIN `votes` ON (posts.post_id=votes.post_id AND votes.user_id=@UserID)
WHERE votes.user_id is null
ORDER BY rand()
LIMIT 1;

  SELECT p.*,
         FLOOR(1 + RAND() * x.m_id) 'rand_ind'
    FROM POSTS p
    JOIN (SELECT MAX(t.id) - 1 'm_id'
            FROM POSTS t) x
   WHERE p.id NOT IN (SELECT v.postid 
                        FROM VOTES v 
                       WHERE v.userid = @UserID)
ORDER BY rand_ind
   LIMIT 1

   SELECT p.*,
          FLOOR(1 + RAND() * x.m_id) 'rand_ind'
     FROM POSTS p
     JOIN (SELECT MAX(t.id) - 1 'm_id'
         FROM POSTS t) x
LEFT JOIN VOTES v ON v.postid = p.id
             AND v.userid = @UserID
    WHERE v.postid IS NULL
 ORDER BY rand_ind
    LIMIT 1

  SELECT p.*,
         FLOOR(1 + RAND() * x.m_id) 'rand_ind'
    FROM POSTS p
    JOIN (SELECT MAX(t.id) - 1 'm_id'
            FROM POSTS t) x
   WHERE NOT EXISTS(SELECT NULL 
                      FROM VOTES v 
                     WHERE v.userid = @UserID
                       AND v.post_id = p.id)
ORDER BY rand_ind
   LIMIT 1