mysql查询帮助？

Question

(
  SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m.dt
  FROM   relationships r
  JOIN notes m ON m.user_id = r.leader
  JOIN user u ON r.leader = u.user_id
  WHERE r.listener ='2'
)


UNION ALL
(
  SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m.dt
  FROM   notes m
  JOIN user u ON m.user_id = u.user_id
  WHERE u.user_id ='2'
)
WHERE dt > '2010-09-20_131830'
ORDER BY dt DESC

这是什么，它询问用户（登录），他们关注的人，并检索他们的消息。 表格如下所示！

我想要添加到此查询，也是用户（登录）更新以及。 但显然用户deosnt跟随自己。 什么是最好的方式我可以做到这一点！

USER_TABLE

 user_id | username
 -------------------
       1 | solomon
       2 | muna

消息表

id    user_id| message
---------------------------------------
 1       1   | this is my first message
 2       1   | this is my second message
 3       2   | this is muna message    

关系表

leader | follower
------------------
     1 | 2

Answer 1

最明显的解决方案是UNION ALL您的查询，使用另一个类似的查询来检索登录用户的消息。 像这样的东西：

(
  SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m.dt
  FROM   relationships r
  JOIN   notes m ON m.user_id = r.leader
  JOIN   user u ON r.leader = u.user_id
  WHERE  r.listener ='".$_SESSION['user_id']."'
)
UNION ALL
(
  SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m.dt
  FROM   notes m
  JOIN   user u ON m.user_id = u.user_id
  WHERE  u.user_id ='".$_SESSION['user_id']."'
);

---

更新：

在更新的查询之后，您不能拥有WHERE子句。 您应该为每个查询都有一个单独的WHERE ，否则使用这样的派生表：

SELECT *
FROM
((
  SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m.dt
  FROM   relationships r
  JOIN   notes m ON m.user_id = r.leader
  JOIN   user u ON r.leader = u.user_id
  WHERE  r.listener ='".$_SESSION['user_id']."'
)
UNION ALL
(
  SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m.dt
  FROM   notes m
  JOIN   user u ON m.user_id = u.user_id
  WHERE  u.user_id ='".$_SESSION['user_id']."'
)) d
WHERE    d.dt > '2010-09-20_131830'
ORDER BY d.dt DESC;

Answer 2

这个怎么样：

SELECT u.username, u.picture, m.id, m.user_note, m.reply_id, m.reply_name, m.dt
FROM notes m
INNER JOIN user u
ON m.user_id = u.user_id
WHERE (m.user_id = '".$_SESSION['user_id']."'
OR m.userID IN (
   SELECT r.leader
   FROM relationships r
   WHERE r.listener ='".$_SESSION['user_id']."'))