计算直接或间接向经理报告的所有下属

Question

我有一个任务有问题。

我需要计算直接或间接向特定经理报告的所有下属（与众不同）

我有一个Employee这样的表：

EMPLOYEE_ID Int,
MANAGER_ID Int,
EMPLOYEE_NAME varchar(200)

例子：

            Alex(1)
    --------------------
    Jhon(2)          Kevin(3)
------------------------------
Mike(4) Amanda(5)  Tom(6) Jery(7)

我只能算直接向经理汇报的员工：

SELECT 
    MANAGER_ID
   ,COUNT(MANAGER_ID) as SubCount
FROM [dbo].[EMPLOYEE]
GROUP BY MANAGER_ID

但是结果是我有这样的事情：

Manager_ID | SubCount
----------------------
1          | 2
2          | 2
3          | 2
----------------------

反而：

Manager_ID | SubCount
----------------------
1          | 6
2          | 2
3          | 2
----------------------

如果有任何建议或想法，我将很高兴。

Answer 1

declare @t table(EMPLOYEE_ID Int,
MANAGER_ID Int,
EMPLOYEE_NAME varchar(200))
insert @t values(1,null,'Alex'),(2,1,'Jhon'),(3,1,'Kevin'),
(4,2,'Mike'),(5,2,'Amanda'),(6,3,'Tom'),(7,3,'Jerry')

;with a as
(
select EMPLOYEE_ID boss,EMPLOYEE_ID from @t t
  where exists (select 1 from @t where t.EMPLOYEE_ID = MANAGER_ID)
union all
select a.boss, t.EMPLOYEE_ID
from @t t join a on t.MANAGER_ID = a.EMPLOYEE_ID
)
--subtracting 1 because it is also counting the manager
select boss, count(*)-1 SubCount from a group by boss
option (maxrecursion 20)