mysql - 多行 COUNT 查询

Question

比如我这里有一个数据

ID    Doctor    Status
1     Wooka     Approved
2     Jamba     Approved
3     Jamba     Approved
4     Wooka     Approved
5     Wooka     Approved
6     Wooka     Approved
7     Wooka     Approved
.    .          .
.    .          .
.    .          .
99    

对于前7行（演示目的，不限于7行）我希望它像这样输出

Doctor    Count
Wooka     5
Jamba     2

虽然我不确定如何在 COUNT() 中做到这一点

SELECT COUNT(*) FROM table WHERE status='Approved'

我真的不知道如何让它灵活地回答我的问题。

Answer 1

SELECT
  t.doctor,
  COUNT(*) AS c
FROM
  table t
WHERE
  t.status = 'Approved'
GROUP BY
  t.doctor

Answer 2

您可以在子查询中使用limit 子句来限制返回的行数，然后使用执行count 的聚合查询包装此查询：

SELECT   doctor, COUNT(*)
FROM     (SELECT   doctor
          FROM     mytable
          WHERE    status = 'Approved'
          ORDER BY id ASC
          LIMIT    7 -- or some other number
         ) t
GROUP BY doctor