Question

我正在尝试选择多次出现的记录，并且是特定部门和其他部门的一部分。

到目前为止，我的查询是：

SELECT employeeCode, employeeName
FROM
    Employees
WHERE
    Department <> 'Technology' 
    AND employeeCode IN (SELECT employeeCode 
            FROM Employees 
            GROUP BY employeeCode HAVING COUNT(*) > 1)

问题是我想选择属于技术部门的员工，但他们也参与其他部门。

所以，他们必须来自技术部门，但他们也可能来自家庭部门。在数据库中它可能看起来像：

1  |  A1  |  Alex  |  Technology
2  |  A2  |  Thor  |  Household
3  |  A3  |  John  |  Cars
4  |  A3  |  John  |  Technology
5  |  A4  |  Kim   |  Technology
6  |  A4  |  Kim   |  Video Games

所以基本上查询应该返回：

  A3  |  John  |  
  A4  |  Kim   |

我认为这是我失踪的一小部分但是...... 有关如何过滤/排序以便始终使用该技术和其他部门的任何想法吗？

不过，我试过搜索，但我找不到像我这样的问题..

Answer 1

如果您希望员工可以加入技术部门和其他部门：

select e.employeeCode, e.employeeName
from employees e
group by e.employeeCode, e.employeeName
having sum(case when e.department = 'Technology' then 1 else 0 end) > 0 and
       count(*) > 1;

这假设表中没有重复项。如果它可以有重复项，请使用count(distinct department) > 1而不是count(*) > 1。

Answer 2

试试这个：

SELECT E.employeeCode, E.employeeName
FROM Employees E
INNER JOIN (SELECT DISTINCT E1.employeeCode, E1.employeeName
            FROM Employees E 
            WHERE E.Department = 'Technology'
           ) AS A ON E.employeeCode = A.employeeCode AND E.employeeName = A.employeeName
GROUP BY E.employeeCode, E.employeeName 
HAVING COUNT(*) > 1;

Answer 3

您可以将EXISTS与相关子查询连接在同一个具有不同条件的表上。

SELECT e1.employeeCode, e1.employeeName
FROM Employees e1
WHERE e1.Department = 'Technology' 
AND EXISTS (SELECT * FROM Employees e2 
            WHERE e1.employeeCode = e2.employeeCode 
            AND e2.Department <> 'Technology')

Answer 4

这适用于您的情况：

SELECT a.employeeCode, a.employeeName
FROM Employees a, Employees b
WHERE 
     a.Department = 'Technology'
     AND
     b.Department <> 'Technology'
     AND 
     a.employeeCode = b.employeeCode
     AND 
     a.employeeID <> b.employeeID

选择多次出现的记录

4 个答案: