Question

我有一个查询，我希望结果根据其“顺序号”返回个人的DOB。它会正确返回个人的姓名，但不会返回正确的DOB。我之所以使用MAX函数，是因为我需要将所有这些数据都放在一行上，如果不使用它，那么如果与一个员工相关的受抚养人不止一个，我将得到多行。

但是，如果有多个依赖项而不是对应于D.SequentialNumber = 1的依赖项，它将拉动最大DOB，这不是我所需要的。我在这里想念什么？

下面是我的查询的一个小样本：

SELECT EIN.EIN, E.First_Name, E.Last_Name, 
Max(IIf(D.SequentialNumber=1,D.DepFirstName)) AS Cov24_First_Name, 
Max(IIf(D.SequentialNumber=1,D.DepLastName)) AS Cov24_Last_Name, 
Max(IIf(D.SequentialNumber=1 AND nz(D.DepDOB) > 0, "")) AS Cov24_SSN,
 Max(IIf(D.SequentialNumber=1 and D.CoveredIndividualSSN >0, "", d.DepDOB)) AS Cov24_DOB

FROM (tblEmp AS E LEFT JOIN tblEIN AS EIN ON E.EIN = EIN.EIN) LEFT JOIN tblDep AS D ON E.Emp_SSN = D.ResponsibleIndividualSSN
GROUP BY EIN.EIN, E.First_Name, E.Middle_Name, E.Last_Name;

Answer 1

我认为情况是倒退的，您可能想要：

Max(IIf(D.SequentialNumber=1 and D.CoveredIndividualSSN >0, d.DepDOB, NULL)) AS Cov24_DOB

Answer 2

我不确定该查询：

SELECT EIN.EIN, E.First_Name, E.Last_Name, 
Max(IIf(D.SequentialNumber=1,D.DepFirstName, "")) AS Cov24_First_Name, 
Max(IIf(D.SequentialNumber=1,D.DepLastName, "")) AS Cov24_Last_Name, 
Max(IIf(D.SequentialNumber=1 AND nz(D.DepDOB) > 0, "", 0)) AS Cov24_SSN,
 Max(IIf(D.SequentialNumber=1 and D.CoveredIndividualSSN >0, "", d.DepDOB, "")) AS Cov24_DOB

FROM (tblEmp AS E LEFT JOIN tblEIN AS EIN ON E.EIN = EIN.EIN) LEFT JOIN tblDep AS D ON E.Emp_SSN = D.ResponsibleIndividualSSN
GROUP BY EIN.EIN, E.First_Name, E.Middle_Name, E.Last_Name;

Answer 3

不确定查询是否应该只限于SequentialNumber = 1的雇员，或者查询是否应处理所有依赖项。为了获得更好的答案，请澄清查询的目的，因为我们也许可以更好地了解下游步骤。

SELECT  DISTINCT
        EIN.EIN
        ,E.First_Name
        ,E.Last_Name
        ,D.DepFirstName AS Cov24_First_Name
        ,D.DepLastName AS Cov24_Last_Name
        ,D.ResponsibleIndividualSSN AS Cov24_SSN
        ,CASE
            WHEN NULLIF(D.CoveredIndividualSSN,'') IS NULL THEN D.DepDOB
        END AS Cov24_DOB
FROM    tblEmp AS E
        LEFT OUTER JOIN tblEIN AS EIN ON E.EIN = EIN.EIN
        LEFT OUTER JOIN tblDep AS D ON E.Emp_SSN = D.ResponsibleIndividualSSN
WHERE   D.SequentialNumber = 1

切换功能和SQL中Null的无效使用

3 个答案: