基于 SQL 中的行 ID 合并列的问题

Posted 2023-02-24

【中文标题】基于 SQL 中的行 ID 合并列的问题

【英文标题】：An Issue with merging columns based on the row ID in SQL

【发布时间】：2019-03-19 11:27:22

【问题描述】：

我需要基于列名称为ID 的行合并comment 列我有一个SQL 查询，以便合并对评论帖子的回复，考虑到回复帖子的计数值，即comment_counts。我需要在新闻提要帖子的单个线程中显示嵌套的 cmets。下面是我的 SQL 查询

SELECT DISTINCT ft.ID as ID, ft.userid, ft.content, ft.timestamp, ft.comments as comment_counts, ftc.comment, ftc.timestamp as comment_timestamp, uq.username, uq.avatar 
FROM users uq, feed_item ft 
LEFT JOIN feed_item_comment ftc ON ftc.postid = ft.ID 
LEFT JOIN user_friends uf ON uf.friendid = ftc.userid 
LEFT JOIN users u ON u.ID = uf.friendid WHERE uq.ID = ft.userid AND ft.userid
IN 
(SELECT u.ID FROM users u WHERE u.ID 
    IN (SELECT uf.friendid FROM user_friends uf WHERE uf.status = '2' AND uf.userid = '".$this->user->info->ID."') 
        OR 
        u.ID 
        IN (SELECT uf.userid FROM user_friends uf WHERE uf.status = '2' AND uf.friendid = '".$this->user->info->ID."') 
        OR
        u.ID = '".$this->user->info->ID."'
) ORDER BY ft.ID DESC, ftc.timestamp DESC

实际结果：

这是从上述查询获得的结果

ID  userid      content                 timestamp   comment_counts  comment         comment_timestamp       username        avatar   
___________________________________________________________________________________________________________________________________________

3   1           This is manju           13:12:31        2           manju comment   13:17:31                manju           1698862132.png   
3   1           This is manju           13:12:31        2           new cmt         14:00:15                manju           1698862132.png   
2   14          How are you doing?      13:06:42        2           Fine            15:00:15                Nishanth        default.png   
2   14          How are you doing?      13:06:42        2           Not Good        15:05:10                Nishanth        default.png   
1   14          How are you?            14:07:00        2           Look Good       20:00:00                Nishanth        default.png   
1   14          How are you?            14:07:00        2           So I'm!         20:10:00                Nishanth        default.png  

对于具有多个 cmets 的单个新闻提要帖子显示在具有嵌套 cmets 的单独提要中。 尽管嵌套的 cmets 反复显示。但有单独的新闻提要线程

预期结果：

ID  userid  content             timestamp   comment_counts  comment1        comment1_timestamp  comment2    comment2_timestamp  username    avatar   
_______________________________________________________________________________________________________________________________________________________

3   1       This is manju       13:12:31        2           manju comment   13:17:31            new cmt     14:00:15            manju       1698862132.png   
2   14      How are you doing?  13:06:42        2           Fine            15:00:15            Not Good    15:05:10            Nishanth    default.png   
1   14      How are you?        14:07:00        2           Look Good       20:00:00            So I'm!     20:10:00            Nishanth    default.png   

我只需要显示嵌套的 cmets（不重复），只有一个新闻帖子作为线程 例如，对于带有“你好吗”消息的单个新闻提要，正如我用“很好”和“不好”评论的那样 对于帖子“你好吗”，它重复了两次。因为我用文字“很好”和“不好”评论了两次 我应该如何防止嵌套的 cmets 在单个新闻提要中作为线程重复两次。

通过使用GROUP_CONCAT(ftc.comment) as replies

ID userid   content         timestamp     comment_counts   comment      comment_timestamp   username   avatar           replies  
__________________________________________________________________________________________________________________________________________________________________________

1   14      How are you?    14:07:00            2           Look Good   20:00:00            Nishanth   default.png   Look Good,Fine,Not Good,manju comment,new cmt,Look...

---

使用查询完成数据库：

SQL Fiddle DEMO

使用GROUP_CONCAT(ftc.comment) 作为回复

ID userid   content         timestamp     comment_counts   comment      comment_timestamp   username   avatar           replies  
__________________________________________________________________________________________________________________________________________________________________________

1   14      How are you?    14:07:00            2           Look Good   20:00:00            Nishanth   default.png   Look Good,Fine,Not Good,manju comment,new cmt,Look...

我应该如何编写 SQL 查询，以便从获得的结果中合并行以获得所需/预期的结果？

【问题讨论】：

您可能需要阅读数据透视表。尽管您想要做的不是典型的枢轴，但您仍在尝试将行转换为列，这就是枢轴所做的。

你的mysql版本是什么@nishanth

MariaDB 服务器版本：10.1.36 @fa06

【参考方案1】：

在下面尝试使用 row_number() 和条件聚合

DEMO

select id, userid,content,timestamp,comment_count,
min(case when seq=1 then comment end) as comment1,
min(case when seq=1 then comment_timestamp end) as commenttime1,
min(case when seq=2 then comment end) as comment2,
min(case when seq=2 then comment_timestamp end) as commenttime2
from
(
select *,row_number() over(partition by id,userid order by comment_timestamp) as seq from 
(SELECT DISTINCT ft.ID as ID, ft.userid, ft.content, ft.timestamp, ft.comments as comment_count, ftc.comment, ftc.timestamp as comment_timestamp, uq.username, uq.avatar FROM users uq,
feed_item ft 
LEFT JOIN feed_item_comment ftc ON ftc.postid = ft.ID
LEFT JOIN user_friends uf ON uf.friendid = ftc.userid 
LEFT JOIN users u ON u.ID = uf.friendid WHERE uq.ID = ft.userid AND ft.userid
IN 
(SELECT u.ID FROM users u WHERE u.ID 
IN (SELECT uf.friendid FROM user_friends uf WHERE uf.status = '2' AND uf.userid = 1) 
OR u.ID IN 
(SELECT uf.userid FROM user_friends uf WHERE uf.status = '2' AND uf.friendid = 1) 
OR
u.ID = 1
)ORDER BY ft.ID DESC, ftc.timestamp DESC)X)Y
group by id, userid,content,timestamp,comment_count

【讨论】：

感谢您的辛勤努力。查询工作正常。但是对于帖子的回复和时间戳的动态值，即comment_count> 2。我应该如何处理您的查询因为我已经附加了（7、2、14，'在你所有的努力之后还不错！'，' 08:13:10', 0, 0, 0);到feed_item_comment 表Click Here

对于 feed_item_comment 和 comment 作为回复值 = Not Good 对于已发布的 content 值 = How are you doing? 来自 feed_item 表 它应该显示在下一个列作为对评论帖子的动态回复的一部分。从而自动为帖子的回复创建一个新列。威尔，你能帮我这样做吗？！

@Nishanthॐ，能否将其添加到您的预期输出中

没问题

@Nishanthॐ maria db 你的版本支持支点吗？