sql - SQL中的计数函数但传入了查询？

Question

我想做这样的事情：

select
    EmployeeID e,
    SupervisorID s
from
    ReportingStructure
where
    count(select SupervisorID from ReportingStructure where EmployeeID = e) > 1

查找拥有多个主管的所有员工的员工 ID 和主管 ID。但我得到一个语法错误：

关键字“select”附近的语法不正确。

')' 附近的语法不正确。

我怎样才能得到这些数据？

Answer 1

您可以使用以下命令将它们放在单独的行上exists：

select EmployeeID, SupervisorID
from ReportingStructure rs
where exists (select 1   
              from ReportingStructure rs2
              where rs2.EmployeeID = rs.EmployeeID and
                    rs2.SupervisorID <> rs.SupervisorID
             );

如果您希望主管排成一排，您可以使用string_agg()：

select EmployeeID, string_agg(SupervisorID, ',')
from ReportingStructure
group by EmployeeID
having count(*) = 2;

Answer 2

使用窗口函数作为

SELECT EmpId, COUNT(1) OVER(PARTITION BY EmpId) Cnt
FROM
(
    VALUES
    (1), (2), (2), (3), (3), (3)
) T(EmpId)

如果你想返回行，Cnt > 1那么

SELECT *
FROM
(
    SELECT EmpId, COUNT(1) OVER(PARTITION BY EmpId) Cnt
    FROM
    (
        VALUES
        (1), (2), (2), (3), (3), (3)
    ) T(EmpId)
) TT
WHERE Cnt > 1; 

Answer 3

似乎您最好使用这样的查询，因为这样您就没有 2 次扫描：

WITH CTE AS(
    SELECT EmployeeID AS e,
           SupervisorID AS s
           COUNT(EmployeeID) OVER (PARTITION BY EmployeeID) AS c
    FROM dbo.ReportingStructure)
SELECT e, s
FROM CTE
WHERE c > 1;

Answer 4

尝试有子句：

SELECT
    EmployeeID e,
    SupervisorID s
FROM
    ReportingStructure
HAVING COUNT(SupervisorID) > 1;