Question

我有一个评论表，允许人们编辑他们的评论。我没有覆盖评论，而是创建了一条新评论，并将其与其父母＆＃34;相关联。另外，我将子信息添加到父级。

id, user_id, comment_id__parent, comment_id__child, comment, created_dt

SQL Fiddle here

现在我的问题是，我希望得到特定用户的所有评论，但只能获得评论的最新更新。

这让我头疼不已，我非常感谢你的投入！

Answer 1

如果你的小提琴是正确的，你应该能够这样做：

SELECT * FROM comments 
 WHERE comment_id__child IS NULL AND user_id=1;

如果您在编辑时始终填充comment_id__child'父级'注释，则此方法有效。

Answer 2

表示uer_id = 1

select * from comments where user_id=1 order by created_dt desc;

Answer 3

这完美无缺！你可以在sql中找到结果。

select * from comments group by user_id having count(id) = 1
UNION
select * from comments where user_id in (select user_id from comments group by user_id having count(id) > 1) and comment_id__child is null and comment_id__parent is not null;

Answer 4

我想我找到了一个解决方案：

SELECT *
FROM comments
WHERE user_id = 1
  AND ( (comment_id__parent IS NULL
         AND comment_id__child IS NULL)
       OR (comment_id__parent IS NOT NULL
           AND comment_id__child IS NULL) )
ORDER BY created_dt DESC

Mysql获取最新一行的自引用关系

4 个答案: