如何按时间戳排序结果顺序(其中之一除外)? [英] How to sort results order by timestamp except one of them?

问题描述

我有一个这样的表:

// 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)

Now I want this result: (please focus on the order)

+----+--------------------+------+------------------+-----------+
| 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? (我想要与SO排序完全一样的东西)

Well how can I do that? (I want something exactly like SO sorting)

这是我的尝试:

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

推荐答案

您需要将表自身连接起来，以确定接受的答案是哪一行.然后可以在ORDER BY中使用该信息:

You need to join the table to itself to determine which row is the accepted answer. Then the information can be used in the ORDER BY:

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

这篇关于如何按时间戳排序结果顺序(其中之一除外)?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！