sql-server - 如何在sql中的case语句中将变量作为null传递

Question

如何在此查询中传递“@abo 为空”和“@rh 为空”......这给出了错误......我正在这样做

select Distinct m.donorId,m.customid, FirstName + ' ' + Isnull(MiddleName,' ') + ' ' + isNull(LastName,'') as donorName  from m_donor as m inner join phlebotomyDetail as phy on m.DonorID=phy.DonorID left outer join  AVIRaw as avi ON  @prefix + RIGHT('000000' + CAST(m.DonorID AS VARCHAR(6)), 6) = avi.sampleid
            Where (m.donorId = @donorid OR @donorid is null) and
            (m.DOB =  @todate OR @todate Is Null) and
            (m.FirstName Like + '%' + @fullname + '%' OR m.MiddleName Like + '%' + @fullname + '%' OR m.LastName Like  +'%' + @fullname + '%' OR @fullname Is Null) and
            (m.cellPhone Like +'%' + @phone + '%' OR m.HomePhone Like + '%' + @phone + '%' OR m.WorkPhone Like + '%' + @phone + '%' OR m.OtherPhone Like + '%' + @phone + '%' OR  @phone Is Null) and
            (m.CustomID Like '%' + @custid OR @custid Is Null) AND
            (phy.BagNumber=@bagno OR @bagno is NULL) AND
            (phy.SegmentNo=@segno OR @segno is NULL ) AND
        (avi.result= CASE WHEN avi.AnalysisName = 'ABO' THEN @abo or @abo is null ELSE CASE WHEN avi.AnalysisName = 'RH' THEN left(@rh,3) or @abo is null END END)

Answer 1

我会尝试类似的东西：

avi.result= 
CASE WHEN avi.AnalysisName = 'ABO' 
THEN @abo 
ELSE 
    CASE WHEN avi.AnalysisName = 'RH' 
    THEN left(@rh,3) 
    END 
END

案例结果的类型必须与 avi.result 的类型兼容。

恕我直言，您应该将 ELSE 放在第二个/内部案例中，或使用以下语法：

avi.result= 
CASE avi.AnalysisName 
    WHEN 'ABO' THEN @abo  
    WHEN 'RH' THEN left(@rh,3)  
    ELSE 'DEF' 
END