Sql server 2005 如何在SQL查询结果中用空值替换0

通过上面的查询，如果员工在表LeaveApplications中没有休假申请记录，则其作为LeaveDays的和（LeaveApplications.LeaveDaysTaken）列返回NULL。我想做的是将值0（零）替换为NULL。我之所以要这样做，是因为我在同一个查询中有一个计算列，其公式取决于返回的LeaveDays，当LeaveDays为NULL时，该公式将失败。我是否可以将0设为空，这样我就可以得到我想要的结果

您可能需要使用

ISNULL

SELECT  EmployeeMaster.EmpNo, Sum(LeaveApplications.LeaveDaysTaken) AS LeaveDays
    FROM  EmployeeMaster  FULL OUTER JOIN
    LeaveApplications ON EmployeeMaster.id = LeaveApplications.EmployeeRecordID INNER JOIN
    LeaveMaster ON EmployeeMaster.id = LeaveMaster.EmpRecordID
    GRoup BY EmployeeMaster.EmpNo
    order by LeaveDays Desc

SELECT  EmployeeMaster.EmpNo, ISNULL(Sum(LeaveApplications.LeaveDaysTaken),0) AS LeaveDays
    FROM  EmployeeMaster  FULL OUTER JOIN
    LeaveApplications ON EmployeeMaster.id = LeaveApplications.EmployeeRecordID INNER JOIN
    LeaveMaster ON EmployeeMaster.id = LeaveMaster.EmpRecordID
    GRoup BY EmployeeMaster.EmpNo
    order by LeaveDays Desc

---

您可能需要使用

ISNULL

SELECT  EmployeeMaster.EmpNo, ISNULL(Sum(LeaveApplications.LeaveDaysTaken),0) AS LeaveDays
    FROM  EmployeeMaster  FULL OUTER JOIN
    LeaveApplications ON EmployeeMaster.id = LeaveApplications.EmployeeRecordID INNER JOIN
    LeaveMaster ON EmployeeMaster.id = LeaveMaster.EmpRecordID
    GRoup BY EmployeeMaster.EmpNo
    order by LeaveDays Desc

使用该功能。

使用该功能