Question

我有一张这样的表：

// Mytable
+----+--------------------+------+------------------+-----------+
| Id |  QuestionOrAnswer  | Type | AcceptedAnswerId | timestamp |
+----+--------------------+------+------------------+-----------+
| 1  | question1          | 0    | 3                | 1         |
| 2  | answer1            | 1    | NULL             | 2         |
| 3  | answer2            | 1    | NULL             | 3         | -- accepted answer
| 4  | answer3            | 1    | NULL             | 4         |
+----+--------------------+------+------------------+-----------+

现在我想要这个结果：（请关注订单）

+----+--------------------+------+------------------+-----------+
| Id |  QuestionOrAnswer  | Type | AcceptedAnswerId | timestamp |
+----+--------------------+------+------------------+-----------+
| 1  | question1          | 0    | 3                | 1         |
| 3  | answer2            | 1    | NULL             | 3         | -- accepted answer 
| 2  | answer1            | 1    | NULL             | 2         |
| 4  | answer3            | 1    | NULL             | 4         |
+----+--------------------+------+------------------+-----------+
//                          ^ 0 means question and 1 means answer

那我该怎么做？（我想要一些与SO排序完全相同的东西）

这是我的尝试：

SELECT * FROM Mytable WHERE 1 ORDER BY Type, {I need to add something here}, timestamp

Answer 1

您需要将表连接到自身以确定哪一行是接受的答案。然后可以在ORDER BY：

中使用该信息

SELECT t.*
FROM Mytable t LEFT JOIN
     Mytable tans
     ON t.id = tans.AcceptedAnswerId
ORDER BY t.Type,
         (tans.id IS NOT NULL) DESC,
         t.timestamp

除了其中一个之外，如何按时间戳排序结果顺序？

1 个答案: