基于 SQL 中的行 ID 合并列的问题

Question

我需要根据列名称 ID 的行合并 comment 列我有一个 SQL 查询，以便合并对评论的回复 posts 正在考虑回复 posts 的计数值，即 comment_counts。我需要在新闻提要 post 的单个线程中显示嵌套评论。
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：

这是上述查询得到的结果

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

对于单个新闻提要 post，多个评论显示在带有嵌套评论的单独提要中。虽然嵌套评论重复显示。但是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

我只需要显示嵌套评论（不重复），只有一个新闻 post 作为一个线程
例如，对于带有消息 "How are you doing" 的单个新闻提要，正如我用 "Fine" 和 "Not Good"
评论的那样对于 post "How are you doing" 它重复两次。因为我已经用文本 "Fine" 和 "Not Good"
评论了两次我应该如何防止嵌套评论作为线程在单个新闻提要中重复两次。

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...

通过查询完成数据库：

SQL Fiddle DEMO

通过使用 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 查询以便合并获得的结果中的行以获得 desired/expected 结果？

Answer 1

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

基于 SQL 中的行 ID 合并列的问题

An Issue with merging columns based on the row ID in SQL

sql

pivot

nested-queries

group-concat

mariadb

通过查询完成数据库：

SQL Fiddle DEMO