Facebook样式墙的mysql查询

Question

我想在我的网站上创建成员(member)墙(facebook 风格)。 基于:

• 成员 friend 的最后评论。
• 成员(member)好友的最新文件。
• 成员文件的最后评论。

表结构:

friendship
userid | friendid | status
---------------------------------
user_table
userid | username
---------------------------------
files_table
file_id | file_title | file_desc | dl_date
---------------------------------
comments_table
comid | userid | file_id | com_date

这是我的 mysql 查询，它有效。但我想知道您的想法以使其变得更好。

--Last files of member's friends
-- Find files of friendship.friendid=$userid
SELECT files_table.file_id AS c1, files_table.file_title AS c2, files_table.file_desc AS c3, files_table.dlauthor AS c4, files_table.dl_date AS date,  IF(files_table.file_id IS NOT NULL, 'Friends_eBooks',FALSE) as Type
    FROM friendship
    LEFT JOIN user_table ON friendship.userid = user_table.userid
    LEFT JOIN files_table ON files_table.dlauthor = user_table.username
    WHERE friendship.friendid = $userid
    AND friendship.STATUS = '1'
-- Find files of friendship.userid=$userid
UNION
SELECT files_table.file_id AS c1, files_table.file_title AS c2, files_table.file_desc AS c3, files_table.dlauthor AS c4, files_table.dl_date AS date,  IF(files_table.file_id IS NOT NULL, 'Friends_eBooks',FALSE) as Type
    FROM friendship
    LEFT JOIN user_table ON friendship.userid = user_table.userid
    LEFT JOIN files_table ON files_table.dlauthor = user_table.username
    WHERE friendship.userid = $userid
    AND friendship.STATUS = '1'
UNION ALL
-- Last comments of member's friends
-- Find comments of friendship.friendid=$userid
SELECT comments_table.comid AS c1, user_table.username AS c2, comments_table.dl_comment AS c3, comments_table.file_id AS c4, comments_table.com_date AS date, IF(comments_table.comid IS NOT NULL, 'Friends_Comments', FALSE) as Type
    FROM friendship
    LEFT JOIN user_table ON friendship.userid = user_table.userid
    LEFT JOIN comments_table ON user_table.userid = comments_table.userid
    WHERE friendship.friendid = $userid
    AND friendship.STATUS = '1'
UNION
-- Find comments of friendship.userid=$userid
SELECT comments_table.comid AS c1, user_table.username AS c2, comments_table.dl_comment AS c3, comments_table.file_id AS c4, comments_table.com_date AS date, IF(comments_table.comid IS NOT NULL, 'Friends_Comments', FALSE) as Type
    FROM friendship
    LEFT JOIN user_table ON friendship.friendid = user_table.userid
    LEFT JOIN comments_table ON user_table.userid = comments_table.userid
    WHERE friendship.userid = $userid
    AND friendship.STATUS = '1'
-- Last comments on member's files
UNION ALL
SELECT comments_table.comid AS c1,user_table.username AS c2,comments_table.dl_comment AS c3, files_table.file_id AS c4,comments_table.com_date AS date, IF(comments_table.comid IS NOT NULL, 'My_Comments', FALSE) as Type
FROM files_table
LEFT JOIN comments_table ON files_table.file_id = comments_table.file_id
LEFT JOIN user_table ON comments_table.userid = user_table.userid
WHERE
(files_table.status=1) AND
(files_table.dlauthor=$userid)
ORDER by date DESC

解释:

id  select_type     table   type    possible_keys   key     key_len     ref     rows    Extra
1   PRIMARY     friendship  ref     friendid    friendid    3   const   22  Using where
1   PRIMARY     user_table  eq_ref  PRIMARY     PRIMARY     4   ketabnak_ebooks.friendship.userid   1    
1   PRIMARY     files_table     ref     dlauthor    dlauthor    92  func    10   
2   UNION   friendship  ref     PRIMARY     PRIMARY     3   const   11  Using where
2   UNION   user_table  const   PRIMARY     PRIMARY     4   const   1    
2   UNION   files_table     ref     dlauthor    dlauthor    92  func    10   
3   UNION   friendship  ref     friendid    friendid    3   const   22  Using where
3   UNION   user_table  eq_ref  PRIMARY     PRIMARY     4   ketabnak_ebooks.friendship.userid   1    
3   UNION   comments_table  ref     userid  userid  3   ketabnak_ebooks.user_table.userid   6    
4   UNION   friendship  ref     PRIMARY     PRIMARY     3   const   11  Using where
4   UNION   user_table  eq_ref  PRIMARY     PRIMARY     4   ketabnak_ebooks.friendship.friendid     1    
4   UNION   comments_table  ref     userid  userid  3   ketabnak_ebooks.user_table.userid   6    
5   UNION   files_table     ref     dlauthor    dlauthor    92  const   294     Using where
5   UNION   comments_table  ref     file_id     file_id     3   ketabnak_ebooks.files_table.file_id     11   
5   UNION   user_table  eq_ref  PRIMARY     PRIMARY     4   ketabnak_ebooks.comments_table.userid   1    
NULL    UNION RESULT    <union1,2,3,4,5>    ALL     NULL    NULL    NULL    NULL    NULL    Using filesort

缺点:

• 查询花费了很多时间。

• 所有表格的列数应该相等。

---

我已经使用Friendship 表找到成员的所有 friend 。 Status 为 1，表示成员的好友已接受好友请求。

首先，Userid = Memberid:

Userid   | Friendid    | Status
1        |      4      |     0
1        |      8      |     1
1        |      9      |     1

然后，我使用 UNION 合并，其中 Friendid = Memberid:

Userid   | Friendid    | Status
2        |      1      |     0
3        |      1      |     0
5        |      1      |     1

Answer 1

让它变得更好的一个想法是停止认为您必须在一个查询中完成所有事情。