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Question

我所拥有的是2张桌子。表A看起来像：

actID; jobnumber; actTypeID; completeDate
1;    2000;       3;      2012-09-04
2;    2000;       4;      2012-09-05
3;    2001;       2;      2012-09-10
4;    2001;       4;      2012-09-05
5;    2001;       5;      2012-09-05
6;    2002;       1;      2012-09-12

表B看起来像：

actTypeID;  actType;  projStatus;
1;     Pick;    Build;
2;     Bid;     Estimate;
3;     PMQC;    QC;
4;     Equipment Test;    QC;
5;     Assembly;    Build;

我需要做的是在其中加入projStatus和actType：

SELECT jobnumber,
    max(completedate) completedate
FROM tableA
GROUP BY jobnumber

不增加返回的记录数，即获取此设置：

jobnumber; actType; projStatus; completedate;
2000;  EquipmentTest; QC;       2012-09-05;
2001;  Bid;           Estimate; 2012-09-10;
2002;  Pick;          Build;    2012-09-12;

我现在正在使用SQL Server 2005，很快就会到2008年。我觉得我错过了这个技巧。

Answer 1

试试这个，

SELECT  x.[jobnumber], x.[actType], x.[projStatus], x.[completeDate]
FROM
(
SELECT a.[actID], a.[jobnumber], b.[actType], b.[projStatus], a.[completeDate],
      ROW_NUMBER() OVER 
     (PARTITiON BY jobnumber ORDER BY [completeDate] DESC ) xx
FROM table1 a
      INNER JOIN table2 b
        on a.[actTypeID]=b.[actTypeID]
) x
WHERE x.xx = 1

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Answer 2

您正在寻找ROW_NUMBER()功能

select jobnumber, actType, projStatus, completedate from
(
    select *, 
        ROW_NUMBER() over (partition by jobnumber order by completedate desc) rn 
    from tablea
) v
    left join tableb
        on v.acttypeid = tableb.actTypeID
where rn = 1

Answer 3

试试这个：

select a.jobnumber, b.actType, b.projStatus, a.completedate
from 
(select jobnumber, 
       max(actTypeId) as actTypeId,
group by jobnumber) groupTableA
inner join tableA a ON a.jobNumber = groupTableA.jobNumber AND a.actTypeId = groupTableA.actTypeId
inner join tableB b ON b.actTypeId = a.actTypeId

限制基于组的选择

3 个答案:

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