嗨,我有这样的mysql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='stackoverflow';
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表,如
列userids
4
3
null
5
1
4
8
6
76
7
21
23
有什么建议吗?感谢
答案 0 :(得分:2)
首先,让我们通过删除所有不必要的子查询来使查询更加标准化:
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='stackoverflow';
然后我们将使用userid
将所有UNION
列放入一个列中,并在前面添加一个INSERT:
INSERT INTO SomeTable (userid)
Select userid
from post_words as qw
where qw.word='stackoverflow'
UNION
Select qfav.userid
from post_words as qw
left join post_favorite as qfav
on qfav.questidfav=qw.questid
where qw.word='stackoverflow'
UNION
Select qfeed.userid
from post_words as qw
left join post_feedback as qfeed
on qfeed.questidfeed=qw.questid
where qw.word='stackoverflow'
UNION
Select qview.userid
from post_words as qw
left join post_stats_view as qview
on qview.questidview=qw.questid
where qw.word='stackoverflow';
可能有一些方法可以避免不得不进行qw.word='stackoverflow'
4次,但现在没有任何灵感来打击我......
确保您的SomeTable
不需要唯一的user_id
列。
另请注意,user_id
vs userid
中你有点不一致 - 我开始清理它然后意识到它可能实际上在你的桌子里,所以你可能需要做一点清理我的清洁工作。