Question

我正在尝试重新编写查询，以便它使用标准联接（在from子句中）而不是旧版本（迁移到SQL服务器，因此强制执行此转换）。我遇到的问题是我的查询版本返回的记录少于原始版本。所以我认为我的外连接之一并不那么外在。感谢您的帮助，特别是如果您实际完成了整个查询。我似乎无法找到关于如何进行这样的转换的任何好的文档。

declare
@startdate datetime, @enddate datetime

select @startdate = dateadd(dd,-6,convert(datetime,convert(varchar,getdate(),101))) 
select @enddate = dateadd(dd,6,@startdate) 

SELECT PAT.CUSID as ID , 
       substring(CPTREC.CompletedDateTime,1,12) AS DateOfService, 
       SUBSTRING(PCMH.ProcedureCode,CHARINDEX('-',PCMH.ProcedureCode)+ 1,50) AS CPT_Code 
FROM cpt_records as CPTREC
left Outer Join ProcedureCodeMH as PCMH 
    on CPTREC.ProcedureCodeRevCount = PCMH.ProcedureCodeRevCount 
        and CPTREC.ProcedureCodeSer= PCMH.ProcedureCodeSer
left outer join Credit as CR 
    on CPTREC.ActInstProcCodeSer = CR.ActInstProcCodeSer 
        and CPTREC.ActInstProcCodeRevCount = CR.ActInstProcCodeRevCount
inner join ActivityInstance as ACTIN 
    on CPTREC.ActivityInstanceSer= ACTIN.ActivityInstanceSer 
        and CPTREC.ActivityInstanceRevCount = ACTIN.ActivityInstanceRevCount
inner join ActivityCapture as ACTCAP 
    on ACTCAP.ActivityInstanceSer= ACTIN.ActivityInstanceSer 
        and ACTCAP.ActivityInstanceRevCount = ACTIN.ActivityInstanceRevCount
inner join ActCaptDiagnosisMH as ACTCAPDMH 
    on ACTCAPDMH.ActivityCaptureSer = ACTCAP.ActivityCaptureSer 
        and ACTCAPDMH.ActivityCaptureRevCount=ACTCAP.ActivityCaptureRevCount
left outer join Department as DEPT 
    on ACTCAP.DepartmentSer = DEPT.DepartmentSer
left outer join Hospitality as HOSP 
    on DEPT.HospitalitySer = HOSP.HospitalitySer
Left outer join Diagnosis as DIAG 
    on ACTCAPDMH.DiagnosisSer = DIAG.DiagnosisSer
inner join TemplateCycle as TEMPCYC 
    on ACTIN.TemplateCycleSer= TEMPCYC.TemplateCycleSer
inner join Template as PLATE 
    on TEMPCYC.TemplateSer = PLATE.TemplateSer
inner join Patent as PAT 
    on PLATE.PatentSer = PAT.PatentSer
Left Outer Join PatentParticular as PATPAR 
    on PAT.PatentSer = PATPAR.PatentSer
inner join PatentDoctor as PATDOC 
    on PAT.PatentSer = PATDOC.PatentSer
inner join Doctor as DOC 
    on PATDOC.ResourceSer = DOC.ResourceSer
WHERE ( CPTREC.CompletedDateTime >= @startdate ) 
    and ( CPTREC.CompletedDateTime < dateadd(dd,1,@enddate) ) 
    and ( CPTREC.ObjectStatus = 'Active' ) 
    and ( PATDOC.OncologistFlag = 0 ) 
    and ( PATDOC.PrimaryFlag = 1 ) 
    and ( PCMH.ProcedureCode like '%77781%' 
            or PCMH.ProcedureCode like '%77782%' 
            or PCMH.ProcedureCode like '%77783%' 
            or PCMH.ProcedureCode like '%77784%' 
            or PCMH.ProcedureCode like '%77785%' 
            or PCMH.ProcedureCode like '%77786%' 
            or PCMH.ProcedureCode like '%77787%')

带回更多记录的原件是

SELECT PAT.CUSID as ID , substring(cpt_records.CompletedDateTime,1,12) AS DateOfService, SUBSTRING(ProcedureCodeMH.ProcedureCode,CHARINDEX('-',ProcedureCodeMH.ProcedureCode)+ 1,50) AS CPT_Code INTO cpt777 FROM cpt_records , ActivityCapture , ActivityInstance , Patent as PAT, ProcedureCodeMH , Template , TemplateCycle , Department , Hospitalityity , Credit , Doctor, PatentDoctor , ActCaptDiagnosisMH , Diagnosis , PatentParticular WHERE ( #cpt_records.ProcedureCodeSer *= ProcedureCodeMH.ProcedureCodeSer) and

( ProcedureCodeMH.ProcedureCodeRevCount =*cpt_records.ProcedureCodeRevCount) and

( ActivityCapture.DepartmentSer *= Department.DepartmentSer) and

( Department.HospitalitySer *= Hospitality.HospitalitySer) and

( ActivityCapture.ActivityCaptureSer *= Credit.ActivityCaptureSer) and

( ActivityCapture.ActivityCaptureRevCount *= Credit.ActivityCaptureRevCount) and

( Credit.ActInstProcCodeSer =* cpt_records.ActInstProcCodeSer) and

( Credit.ActInstProcCodeRevCount =* cpt_records.ActInstProcCodeRevCount) and

( Patent.PatentSer *= PatentParticular.PatentSer) and

( cpt_records.ActivityInstanceSer = ActivityInstance.ActivityInstanceSer ) and

(cpt_records.ActivityInstanceRevCount = ActivityInstance.ActivityInstanceRevCount ) and

( ActivityInstance.ActivityInstanceSer = ActivityCapture.ActivityInstanceSer ) and

( ActivityInstance.ActivityInstanceRevCount = ActivityCapture.ActivityInstanceRevCount ) and

( Patent.PatentSer = Template.PatentSer ) and

( Template.TemplateSer = TemplateCycle.TemplateSer ) and

( TemplateCycle.TemplateCycleSer = ActivityInstance.TemplateCycleSer ) and

( Patent.PatentSer = PatentDoctor.PatentSer ) and

( PatentDoctor.ResourceSer = Doctor.ResourceSer ) and

( ActivityCapture.ActivityCaptureSer = ActCaptDiagnosisMH.ActivityCaptureSer ) and

( ActivityCapture.ActivityCaptureRevCount = ActCaptDiagnosisMH.ActivityCaptureRevCount ) and (cpt_records.CompletedDateTime >= @startdate ) and

( cpt_records.CompletedDateTime < dateadd(dd,1,@enddate) ) and

( cpt_records.ObjectStatus = 'Active' ) and

( PatentDoctor.OncologistFlag = 0 ) and

( PatentDoctor.PrimaryFlag = 1 ) and

( ActCaptDiagnosisMH.DiagnosisSer *= Diagnosis.DiagnosisSer) and

( ProcedureCodeMH.ProcedureCode like '%77781%' or ProcedureCodeMH.ProcedureCode like '%77782%' or ProcedureCodeMH.ProcedureCode like '%77783%' or ProcedureCodeMH.ProcedureCode like '%77784%' or ProcedureCodeMH.ProcedureCode like '%77785%' or ProcedureCodeMH.ProcedureCode like '%77786%' or ProcedureCodeMH.ProcedureCode like '%77787%')

Answer 1

问题是左连接为没有找到匹配行的连接列值返回空值，但是您正在检查where子句中的那些列值，但where谓词是在所有行被连接之后执行，因此它们永远不会匹配，并且您的外连接会被沉没。

即，此示例查询：

select * from table1 t1 left join table2 t2 on t2.fk = t1.id where t2.col1 = 'x'

将从不返回table2中没有相应行的任何行，因为col1将为null，并与{{1}进行比较} null，false除外。

要解决此问题，您需要将测试移到col1 is null子句中，以便在进行连接时进行的比较，如下所示：

ON

现在左连接仍会在匹配键时返回行，并应用额外的谓词来进一步细化匹配。

在您的情况下，您正在对select * from table1 t1 left join table2 t2 on t2.fk = t1.id and t2.col1 = 'x'进行外部（left）联接，但在ProcedureCodeMH as PCMH子句中测试PCMH的列，类似于上面的第一个示例

然后重写您的查询（参见内容评论，了解更改的位置）：

WHERE

注意：SELECT PAT.CUSID as ID , substring(CPTREC.CompletedDateTime,1,12) AS DateOfService, SUBSTRING(PCMH.ProcedureCode,CHARINDEX('-',PCMH.ProcedureCode)+ 1,50) AS CPT_Code FROM cpt_records as CPTREC left Outer Join ProcedureCodeMH as PCMH on CPTREC.ProcedureCodeRevCount = PCMH.ProcedureCodeRevCount and CPTREC.ProcedureCodeSer= PCMH.ProcedureCodeSer -- MOVED THIS TEST FROM WHERE CLAUSE TO HERE and ( PCMH.ProcedureCode like '%77781%' or PCMH.ProcedureCode like '%77782%' or PCMH.ProcedureCode like '%77783%' or PCMH.ProcedureCode like '%77784%' or PCMH.ProcedureCode like '%77785%' or PCMH.ProcedureCode like '%77786%' or PCMH.ProcedureCode like '%77787%') left outer join Credit as CR on CPTREC.ActInstProcCodeSer = CR.ActInstProcCodeSer and CPTREC.ActInstProcCodeRevCount = CR.ActInstProcCodeRevCount inner join ActivityInstance as ACTIN on CPTREC.ActivityInstanceSer= ACTIN.ActivityInstanceSer and CPTREC.ActivityInstanceRevCount = ACTIN.ActivityInstanceRevCount inner join ActivityCapture as ACTCAP on ACTCAP.ActivityInstanceSer= ACTIN.ActivityInstanceSer and ACTCAP.ActivityInstanceRevCount = ACTIN.ActivityInstanceRevCount inner join ActCaptDiagnosisMH as ACTCAPDMH on ACTCAPDMH.ActivityCaptureSer = ACTCAP.ActivityCaptureSer and ACTCAPDMH.ActivityCaptureRevCount=ACTCAP.ActivityCaptureRevCount left outer join Department as DEPT on ACTCAP.DepartmentSer = DEPT.DepartmentSer left outer join Hospitality as HOSP on DEPT.HospitalitySer = HOSP.HospitalitySer Left outer join Diagnosis as DIAG on ACTCAPDMH.DiagnosisSer = DIAG.DiagnosisSer inner join TemplateCycle as TEMPCYC on ACTIN.TemplateCycleSer= TEMPCYC.TemplateCycleSer inner join Template as PLATE on TEMPCYC.TemplateSer = PLATE.TemplateSer inner join Patent as PAT on PLATE.PatentSer = PAT.PatentSer Left Outer Join PatentParticular as PATPAR on PAT.PatentSer = PATPAR.PatentSer inner join PatentDoctor as PATDOC on PAT.PatentSer = PATDOC.PatentSer inner join Doctor as DOC on PATDOC.ResourceSer = DOC.ResourceSer WHERE CPTREC.CompletedDateTime >= @startdate and CPTREC.CompletedDateTime < dateadd(dd,1,@enddate) and CPTREC.ObjectStatus = 'Active' and PATDOC.OncologistFlag = 0 and PATDOC.PrimaryFlag = 1可以简化为inner join - join是默认的连接类型。

将非标准联接转换为标准联接

1 个答案: