MYSQL ORDER BY CASE问题

  • Z时代
  • 2024-01-10
  • 分类：问答

我有一个这样的数据库：

-------------------------------------------------------------------
|   id_one   |   id_two   |   timestamp_one   |   timestamp_two   |
-------------------------------------------------------------------
|     27     |     35     |        9:30       |        NULL       |
-------------------------------------------------------------------
|     35     |     27     |        NULL       |        9:35       |
-------------------------------------------------------------------
|     27     |     35     |        9:34       |        NULL       |
-------------------------------------------------------------------
|     35     |     27     |        NULL       |        9:33       |
-------------------------------------------------------------------

我需要拉全部4行

ORDER BY 'timestamp_one' if 'id_one'=27 or 
ORDER BY 'timestamp_two' if 'id_one'=27

这是我现在的声明：

SELECT * FROM tablename 
WHERE id_one=27 OR id_two=27 
ORDER BY 
  CASE WHEN id_one=27 THEN timestamp_one END DESC, 
  CASE WHEN id_two=27 THEN timestamp_two END DESC

这很好，因为输出如下：

-------------------------------------------------------------------
|   id_one   |   id_two   |   timestamp_one   |   timestamp_two   |
-------------------------------------------------------------------
|     27     |     35     |        9:30       |        NULL       |
-------------------------------------------------------------------
|     27     |     35     |        9:34       |        NULL       |
-------------------------------------------------------------------
|     35     |     27     |        NULL       |        9:33       |
-------------------------------------------------------------------
|     35     |     27     |        NULL       |        9:35       |
-------------------------------------------------------------------

但是我需要两个timestamp列进行排序，就像它们是一列一样，因此它的排序如下：

-------------------------------------------------------------------
|   id_one   |   id_two   |   timestamp_one   |   timestamp_two   |
-------------------------------------------------------------------
|     27     |     35     |        9:30       |        NULL       |
-------------------------------------------------------------------
|     35     |     27     |        NULL       |        9:33       |
-------------------------------------------------------------------
|     27     |     35     |        9:34       |        NULL       |
-------------------------------------------------------------------
|     35     |     27     |        NULL       |        9:35       |
-------------------------------------------------------------------

我希望这是有道理的。本质上，我试图拥有两个特定于WHERE条件的ORDER BY列。然后，为该行选择正确的ORDER

BY列后，它将按时间戳整体对ROWS进行排序。

回答：

SELECT id_one, id_two, timestamp_one, timestamp_two      
FROM tablename 
WHERE id_one = 27 
    OR id_two = 27 
ORDER BY 
    CASE 
        WHEN id_one=27 THEN timestamp_one 
        WHEN id_two=27 THEN timestamp_two 
    END DESC

以上是 MYSQL ORDER BY CASE问题 的全部内容， 来源链接： utcz.com/qa/400316.html

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