MySQL如何从GROUP BY进行计数

Question

 date | userid | companyid 12.8.14 | 1 | 1 12.8.14 | 2 | 2 12.8.14 | 3 | 1 

我有一张上面的桌子。 通过正常查询，很容易从表中计算出多少个公司1 。

我的问题是：如果我的查询是select * from table where companyid = '1' group by date ，那么我如何才能得到mysql_num_row等于2的公司1和userid是1和3 ？

select * from table where companyid = '1' group by date只会返回mysql_num_row等于1并返回12.8.14 | 1 | 1 12.8.14 | 1 | 1

Answer 1

您可以嵌套查询以获取公司一条目的总和，然后将该嵌套查询与外部查询连接：

SELECT ABB2.*, ABB1.mysql_num_row
FROM `table` AS ABB2
  JOIN 
      (SELECT companyid, COUNT(userid) AS mysql_num_row
      FROM `table`
      GROUP BY companyid) AS ABB1 ON ABB1.companyid = ABB2.companyid
WHERE ABB2.companyid = 1;

例

Answer 2

也尝试这样

select *,(select count(*) from table1 where companyid=a.companyid) as count 
from t  as a where companyid=1

Answer 3

你自找的：

select date,companyid,count(*)
from table
where userid = 1
group by date,companyid