mysql向一列插入多列数据

Question

您好，我mysql有这样的查询

Select  postid, user_id , qfav.userid, qfeed.userid, qview.userid  
from post_words as qw 
left join (Select userid, postid as postidfav  from post_favorite) as  qfav 
    on qfav.questidfav=qw.questid 
left join (Select userid, questid as questidfeed from post_feedback) as  qfeed 
    on qfeed.questidfeed=qw.questid 
left join (Select userid, questid as questidview from post_stats_view) as qview 
    on qview.questidview=qw.questid 
where qw.word='Whosebug';

结果

questid user_id  userid  userid userid

 100       4       3      null    5
  25       1       4       8      6
 200       76      7       21     23

我如何将列值插入另一个 table 像

这样的列

有什么建议吗？谢谢

Answer 1

首先，让我们删除所有不必要的子查询，使查询更标准一些：

Select  postid, user_id , qfav.userid, qfeed.userid, qview.userid  
from post_words as qw 
left join post_favorite as qfav 
    on qfav.questidfav=qw.questid 
left join post_feedback as qfeed
    on qfeed.questidfeed=qw.questid 
left join post_stats_view as qview
    on qview.questidview=qw.questid 
where qw.word='Whosebug';

然后我们将使用 UNION 将所有 userid 列合并为一个列，并在前面添加一个 INSERT：

INSERT INTO SomeTable (userid) 
Select  userid
  from post_words as qw 
  where qw.word='Whosebug'
UNION
Select  qfav.userid
  from post_words as qw 
  left join post_favorite as qfav 
    on qfav.questidfav=qw.questid 
  where qw.word='Whosebug'
UNION
Select  qfeed.userid
  from post_words as qw 
  left join post_feedback as qfeed
    on qfeed.questidfeed=qw.questid 
  where qw.word='Whosebug'
UNION
  Select  qview.userid  
  from post_words as qw 
  left join post_stats_view as qview
    on qview.questidview=qw.questid 
  where qw.word='Whosebug';

可能有一些方法可以避免 qw.word='Whosebug' 4 次，但现在我没有灵感...

确保您的 SomeTable 不需要唯一的 user_id 列。

另请注意，您在 user_id 与 userid 中有点不一致 - 我开始清理它，然后意识到它实际上可能在您的表中，因此您可能必须这样做我的打扫卫生稍微打扫一下。

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