Question

我试图在多个表中进行计数（*），但是将它们放在一个组中。

我在mysql中的查询是：

SELECT
  (SELECT COUNT(*) as 'Orders', Customer FROM table WHERE `date` = CURRENT_DATE()) as Client1, 
  (SELECT COUNT(*) as 'Orders', Customer FROM table2 WHERE `date` = CURRENT_DATE()) as Client2,
  (SELECT COUNT(*) as 'Orders', Customer FROM table3 WHERE `date` = CURRENT_DATE()) as Client3
  group by Customer

这就是我想回来的地方：

+-------------+---------+---------+---------+
| Customer    | Client1 | Client2 | Client3 |
+-------------+---------+---------+---------+
| John Doe    | 88      | 19      | 0       |
+-------------+---------+---------+---------+
| Mary P      | 0       | 32      | 0       |
+-------------+---------+---------+---------+
| Scott K     | 11      | 25      | 31      |
+-------------+---------+---------+---------+

我唯一关心的是客户不会存在于其他表中，例如 - John Doe只是table1中的客户 - 而不是table2或table3。

与Mary P相同 - 她只是table2中的客户，而不是table1或table 3等。

Answer 1

select a.Customer, sum(client1), sum(client2), sum(client3)
from
(
    select Customer, count(*) as client1, 0 as client2, 0 as client3 from table WHERE `date` = CURRENT_DATE() group by Customer
    union all
    select Customer, 0, count(*), 0 from table2 WHERE `date` = CURRENT_DATE() group by Customer
    union all
    select Customer, 0, 0, count(*) from table3 WHERE `date` = CURRENT_DATE() group by Customer
) as a
group by a.Customer

Answer 2

请在联盟之前使用() 像

  select a.Customer, sum(client1), sum(client2), sum(client3)
    from
    (
        (select Customer, count(*) as client1, 0 as client2, 0 as client3 from table WHERE `date` = CURRENT_DATE() group by Customer)
        union all
        (select Customer, 0, count(*), 0 from table2 WHERE `date` = CURRENT_DATE() group by Customer)
        union all
        (select Customer, 0, 0, count(*) from table3 WHERE `date` = CURRENT_DATE() group by Customer)
    ) as a
    group by a.Customer

group by count（*）mysql多个表

2 个答案: