mysql查詢幫助？

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

這是什么，它詢問用戶（登錄），他們關注的人，並檢索他們的消息。 表格如下所示！

我想要添加到此查詢，也是用戶（登錄）更新以及。 但顯然用戶deosnt跟隨自己。 什么是最好的方式我可以做到這一點！

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    

關系表

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

Answer 1

最明顯的解決方案是UNION ALL您的查詢，使用另一個類似的查詢來檢索登錄用戶的消息。 像這樣的東西：

(
  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：

在更新的查詢之后，您不能擁有WHERE子句。 您應該為每個查詢都有一個單獨的WHERE ，否則使用這樣的派生表：

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

這個怎么樣：

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']."'))