Question

我有一个朋友脚本，我在列表上显示朋友，但我想按他们的last active订购。我有这个代码

SELECT user_one, user_two FROM frnds WHERE user_one='$my_id' OR user_two='$my_id'

表格

|id|user_one|user_two|
| 1|       1|      19|
| 2|       4|       1|
| 3|       9|     403|`

lastactive位于users表格中。

谢谢！：）

Answer 1

你在找这样的东西吗？

SELECT u.name friend_name, u.lastactive
  FROM
(
  SELECT IF(user_one = ?, user_two, user_one) friend
    FROM frnds
   WHERE ? IN(user_one, user_two) 
) f JOIN users u
    ON f.friend = u.id
 ORDER BY u.lastactive DESC;

或

SELECT u.name friend_name, u.lastactive
  FROM 
(
  SELECT user_one friend
    FROM frnds
   WHERE user_two = ?
  UNION ALL
  SELECT user_two
    FROM frnds
   WHERE user_one = ?
) f JOIN users u
    ON f.friend = u.id
 ORDER BY u.lastactive DESC;

注意：在两个查询?中都是$my_id的占位符

样本输出（在两种情况下）：

| FRIEND_NAME |                      LASTACTIVE |
|-------------|---------------------------------|
|     User 19 |    March, 03 2014 20:30:57+0000 |
|      User 4 | February, 24 2014 20:30:57+0000 |

这是 SQLFiddle 演示

JOIN和ORDER BY - mysql_query

1 个答案: