ISNULL（Count（x），0）为null时不返回0

Question

我有以下代码：

SELECT     FirstName, LastName,
(SELECT ISNULL(COUNT(UP1.EmailAddress), 0) AS HasEmail 
     From dbo.UserProfiles AS UP1 
     WHERE (NOT (UP1.EmailAddress IS NULL)) AND (CreatedBy = dbo.UserProfiles.UserID)
     GROUP BY CreatedBy) AS EmailEnteredCount FROM dbo.UserProfiles WHERE (IsStaff = 1)

样本结果：

姓氏EmailEnteredCount

帐单为空

拉尔森51

佳士得30

零值

senac NULL

该代码可以正确执行，但有一个例外，当未找到任何记录而不是预期的0时，它将返回一个空值。

更新：这将返回我要完成的工作，只是需要一个更清洁的解决方案。我真的不认为我需要创建一个临时表来替换一个空值。

drop table #tt
                    select userid,firstname, lastname, 
                    (
                      SELECT     count(*) AS HasEmail
                      FROM         dbo.UserProfiles AS UP1
                      WHERE     (UP1.EmailAddress IS NOT NULL)AND (UP1.CreatedBy = UserProfiles.UserId) and (datecreated between @startdate and @enddate)
                      GROUP BY CreatedBy
                    ) as EmailCount
                    into #tt
                    from dbo.UserProfiles where isstaff = 1

                    select userid,firstname, lastname, ISNULL(EmailCount,0) As EmailCount from #tt

任何帮助，将不胜感激。

谢谢克里斯

Answer 1

您需要将isnull函数移到相关子查询之外，如下所示：

SELECT  FirstName, 
        LastName,
        IsNull((
            SELECT  COUNT(UP1.EmailAddress) AS HasEmail 
            From    dbo.UserProfiles AS UP1 
            WHERE   (NOT (UP1.EmailAddress IS NULL)) 
                    AND (CreatedBy = dbo.UserProfiles.UserID)
            GROUP BY CreatedBy), 0) AS EmailEnteredCount 
FROM    dbo.UserProfiles 
WHERE   (IsStaff = 1)