如何选择帖子的最后编辑版本？

Question

这是表结构:

+----+-----------------------------+-----------+
| id |       post_content          | edited_id |
+----+-----------------------------+-----------+
| 1  | content 1                   | NULL      |
| 2  | content 2                   | NULL      |
| 3  | content 1 (edited)          | 1         |
| 4  | content 3                   | NULL      |
| 5  | content 4                   | NULL      |
| 6  | content 4 (edited)          | 5         |
| 7  | content 1 (edited)          | 1         |
+----+-----------------------------+-----------+

现在我想选择每篇文章的最新编辑版本.所以这是预期的结果:

+----+-----------------------------+-----------+
| id |       post_content          | edited_id |
+----+-----------------------------+-----------+
| 7  | content 1 (edited)          | 1         |
| 2  | content 2                   | NULL      |
| 4  | content 3                   | NULL      |
| 6  | content 4 (edited)          | 5         |
+----+-----------------------------+-----------+

我怎样才能做到这一点？

Answer 1

select max(id), post_content, edited_id from post where edited_id is not null group by edited_id
union
select id, post_content, edited_id from post where edited_id is null and id not in (select edited_id from post where edited_id is not null)