Question

我有一个表，我需要使用另一个表中的select来更新它。

我的想法：

UPDATE articles, 
    (SELECT  count(*) AS count FROM nots WHERE otherID=243 GROUP BY number) AS cnots 
SET articles.first=(SELECT count FROM cnots WHERE number=1),
    articles.second=(SELECT count FROM cnots WHERE number=2),
    articles.third=(SELECT count FROM cnots WHERE number=3)
WHERE articles.ID=243

查询引发错误＆＃34;表＆＃39; mydb.cnots＆＃39;不存在＆＃34;。

我可以用3种不同的选择来做，但我不想，有什么想法吗？

Answer 1

(SELECT  count(*) AS count FROM nots WHERE otherID=243 GROUP BY number) AS cnots

这里的这一行应该好像有一个表作为cnots。这应该是这样的

(SELECT  count(*) FROM cnots WHERE otherID=243 GROUP BY number) AS cnots

Answer 2

怎么样

- ＆GT;

UPDATE articles 
   SET articles.first=(SELECT cnots.count
                       FROM 
                      (SELECT  count(*) AS count 
                             FROM nots WHERE otherID=243 GROUP BY number) AS cnots
                                WHERE number=1)

.......

Answer 3

好的，这是我发现的最佳解决方案：

update articles, 
       (SELECT  sum(case when number = 1 then 1 else 0 end) AS first,
                sum(case when number = 2 then 1 else 0 end) AS second,
                sum(case when number = 3 then 1 else 0 end) AS third
                FROM nots WHERE otherID=243 ) AS cnots 
       SET articles.first=cnots.first,
           articles.second=cnots.second,
           articles.third=cnots.third
       WHERE articles.ID=243

Mysql-使用group by从select中更新多个列

3 个答案: