SQL 多 CASE 语句返回 0 而不是 NULL

Question

我有以下 SQL Case 语句，只要年份匹配 MF.Date & M.MemberCurrentYear，它就可以完美运行。会出现年份不匹配的情况，这会返回 NULL 的余额。我希望它返回零。

SELECT SUM(CASE WHEN Type = 1 THEN Amount ELSE Amount * - 1 END) AS Balance
FROM dbo.MemberFinancials AS MF 
INNER JOIN dbo.Members AS M ON MF.MemberID = M.MemberID 
  AND DATEPART(yyyy, MF.Date) = M.MemberCurrentYear 
INNER JOIN dbo.FinancialTypes AS FT ON MF.FinancialTypeID = FT.FinancialTypeID

谢谢

Answer 1

SELECT     

     ISNULL(SUM(CASE WHEN Type = 1 THEN Amount ELSE Amount * - 1 END),0) AS Balance
FROM         dbo.MemberFinancials AS MF INNER JOIN
                      dbo.Members AS M ON MF.MemberID = M.MemberID AND DATEPART(yyyy, MF.Date) = M.MemberCurrentYear INNER JOIN
                      dbo.FinancialTypes AS FT ON MF.FinancialTypeID = FT.FinancialTypeID

使用 ISNULL(如果您愿意，也可以使用 COALESCE...)