每个部门仅选择一名员工

Question

我希望每个部门（EmpDepartment）都有一名员工，例如在我的表中有：

• 3名拥有EmpDepartment 1的员工
• 2名拥有EmpDepartment 2和
的员工
• 1名拥有EmpDepartment 3的员工

我希望每个独立部门的任何一名员工的EmployeeId，EmployeeName和EmpDepartment。

Answer 1

使用这样的窗口功能：

SELECT * FROM 
(
    SELECT EmployeeID, EmployeeName, EmployeeEmail
         , ROW_NUMBER() OVER (PARTITION BY EmpDepartment ORDER BY NEWID()) AS rn
    FROM   dbo.Employee
) x 
WHERE x.rn = 1

如果您有要用来挑选员工的业务规则，则可以在窗口功能中添加一个order子句

例如

SELECT *
FROM (
  SELECT 
     E.*,
     ROW_NUMBER() OVER (PARTITION BY EmpDepartment) AS RN
  FROM Employee
) X
WHERE X.RN = 1

Answer 2

由于要通过NEWID（）订购，因此每个部门都有一名随机雇员。

Optional<Node> wrappedNode1 = ((JavassistClassDeclaration) declaringType).toAst();

如果需要，可以将order by子句更改为其他内容。

Answer 3

SELECT Top(1) EmployeeID, EmployeeName, EMPDeptartment  FROM Employee WHERE EmpDetpartment = 1

UNION

SELECT Top(1) EmployeeID, EmployeeName, EMPDeptartment  FROM Employee WHERE EmpDetpartment = 2

UNION

SELECT Top(1) EmployeeID, EmployeeName, EMPDeptartment  FROM Employee WHERE EmpDetpartment = 3

Answer 4

这将返回该部门中具有最低EmployeeID的每个部门的员工（因为结果中哪个员工并不重要）：

SELECT e.* FROM Employee e
WHERE NOT EXISTS (
  SELECT 1 FROM Employee 
  WHERE EmpDepartment = e.EmpDepartment AND EmployeeID < e.EmployeeID
)

Answer 5

您可以使用行号查找特定部门更改为1,2的任何员工，...等

Select department, employee
from (
   Select department, employee, 
      row_number() over (partition by department order by employee) rn
) 
where rn =1;

或使用简单分组依据

Select department, max(employee)
from table 
group by department