SQL-如何在结果中排​​除具有NULL值的分组

Question

我正在尝试从结果中排除包含NULL值的分组。 我正在使用以下查询：

SELECT EmployeeID,AppointmentEndDate
FROM Appointment
WHERE EmployeeID IN
    (SELECT EmployeeID 
            FROM Appointment
    GROUP BY EmployeeID
     HAVING COUNT(*) > 1 )
GROUP BY EmployeeID,AppointmentEndDate
ORDER BY EmployeeID

结果集如下所示：

EmployeeID  AppointmentEndDate
1   NULL
1   2000-06-30 00:00:00.000
2   NULL
2   2006-06-30 00:00:00.000
2   2014-06-30 00:00:00.000
3   2006-07-02 00:00:00.000
3   2015-06-30 00:00:00.000
5   NULL
5   2001-12-31 00:00:00.000
5   2002-06-30 00:00:00.000

因此，在这种特定情况下，我只想查看EmployeeID 3的记录

非常感谢，A

Answer 1

您可以简化查询，以获取表中的约会日期从未为NULL的唯一employeeId

SELECT EmployeeID
FROM Appointment
WHERE AppointmentEndDate IS NOT NULL
GROUP BY EmployeeID
HAVING COUNT(*) > 1

或者，如果您不关心表中不为null的employeeId是否在表中出现多次，则可以使用distinct

SELECT DISTINCT EmployeeID
FROM Appointment
WHERE AppointmentEndDate IS NOT NULL

如果您希望获得employeeIds的最后约会日期，GROUP BY将帮助您使用聚合函数

SELECT EmployeeID , MAX(AppointmentEndDate) as LastDateOfAppointment
FROM Appointment
WHERE AppointmentEndDate IS NOT NULL
GROUP BY EmployeeID
HAVING COUNT(*) > 1

Answer 2

您可以尝试如下操作：

WITH CTE AS
(

    YourQueryHere

)
SELECT *
FROM CTE
WHERE NOT EXISTS(SELECT 1 FROM CTE AS x WHERE x.EmployeeID=CTE.EmployeeID AND AppointmentEndDate IS NULL)

Answer 3

使用“ WHERE NOT EXISTS [Subselect]”（WHERE NOT EXISTS [Subselect]）来筛选出具有一个或多个记录且AppointementEndDate为空的员工。 假设这是您要尝试执行的操作。

SELECT EmployeeID,AppointmentEndDate
FROM Appointment
WHERE NOT EXISTS(SELECT TOP 1 1 
                 FROM Appointment AS A 
                 WHERE Appointment.EmployeeID = A.EmployeeID
                 AND A.AppointmentEndDate IS NULL)
GROUP BY EmployeeID,AppointmentEndDate
ORDER BY EmployeeID

Answer 4

You Should Try This It's Working.....

SELECT EmployeeID,AppointmentEndDate
FROM Appointment
WHERE EmployeeID NOT IN
    (SELECT EmployeeID 
            FROM Appointment
    WHERE AppointmentEndDate IS NULL
    GROUP BY EmployeeID
      )
GROUP BY EmployeeID,AppointmentEndDate
ORDER BY EmployeeID

Answer 5

不知道GROUP BY提供什么值，但是我留给它是为了防止这是一个精简的示例。

Declare @Appointment table (EmployeeID int,AppointmentEndDate DateTime)
Insert Into @Appointment values
(1,NULL),
(1,'2000-06-30 00:00:00.000'),
(2,NULL),
(2,'2006-06-30 00:00:00.000'),
(2,'2014-06-30 00:00:00.000'),
(3,'2006-07-02 00:00:00.000'),
(3,'2015-06-30 00:00:00.000'),
(5,NULL),
(5,'2001-12-31 00:00:00.000'),
(5,'2002-06-30 00:00:00.000')

Select EmployeeID,AppointmentEndDate
 From  @Appointment
 Where EmployeeID NOT IN (Select Distinct EmployeeID From @Appointment Where AppointmentEndDate Is NULL )
 Group By EmployeeID,AppointmentEndDate
 Order ByEmployeeID

退货

EmployeeID  AppointmentEndDate
3           2006-07-02 00:00:00.000
3           2015-06-30 00:00:00.000