Question

我有一个当前查询，它返回查询参数的所有值。

但是当我只想显示每个最新行时，它会返回较旧的值，我已经开始使用max()和DISTINCT，但我无法获得输出我想要

当前代码

SELECT 
IME.TP AS [Time],
IU.FS07 AS [LID], 
IU.I AS [LNum],
IME.TPL AS [Location],
(SELECT CASE 
        WHEN IME.TPL = 'Y' 
        THEN 'GTG' 
        ELSE 
            (SELECT CASE 
                    WHEN IME.TPL = 'V' 
                    THEN 'WAIT' 
                    ELSE 'WAIT' 
                    END) 
        END) AS [Go To]

FROM
IU 
INNER JOIN IUFV ON IU.G = IUFV.UG
INNER JOIN IME ON IUFV.G = IME.UFVG

当前输出

 ________________________________________________________________
|Time                       LID     LNum        Location    Go To|
|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|
|2012-07-08 10:54:57.837    CCC     CCC111      V           WAIT |
|2012-07-08 12:15:07.000    CCC     CCC111      Y           GTG  |
|2012-07-17 06:58:33.417    CCC     CCC111      T           WAIT |
|2012-08-09 03:51:20.750    BBB     BBB222      Y           GTG  |
|2012-08-09 04:06:13.473    BBB     BBB222      Y           GTG  |
 ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

所需输出

 ________________________________________________________________
|Time                       LID     LNum        Location    Go To|
|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|
|2012-07-17 06:58:33.417    CCC     CCC111      T           WAIT |
|2012-08-09 04:06:13.473    BBB     BBB222      Y           GTG  |
 ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Answer 1

SELECT 
IME.TP AS [Time],
IU.FS07 AS [LID], 
IU.I AS [LNum],
IME.TPL AS [Location],
(SELECT CASE 
        WHEN IME.TPL = 'Y' 
        THEN 'GTG' 
        ELSE 'WAIT'
        END) AS [Go To]

FROM
IU 
INNER JOIN IUFV ON IU.G = IUFV.UG
INNER JOIN IME ON IUFV.G = IME.UFVG
INNER JOIN (Select Max(time) MTime, UFVG from IME
GROUP BY UFVG) B
 on B.UFVG=IUFV.G
 and B.MTime = IME.Time

如果没有更深入的潜水，我不确定是否可以消除额外的连接，并且首先从IME获得结果。但是对TPL的需求可能需要单独的连接

SELECT 
IME.TP AS [Time],
IU.FS07 AS [LID], 
IU.I AS [LNum],
IME.TPL AS [Location],
(SELECT CASE 
        WHEN IME.TPL = 'Y' 
        THEN 'GTG' 
        ELSE 'WAIT'
        END) AS [Go To]

FROM
IU 
INNER JOIN IUFV ON IU.G = IUFV.UG
INNER JOIN (Select Max(time) MTime, UFVG from IME
GROUP BY UFVG) B
 on B.UFVG=IUFV.G
 and B.MTime = IME.Time

Answer 2

这是基本方法。我假设您在组中没有重复的时间戳。

select *
from T
    inner join (select GrpId, max(TimeStmp) from T group by GrpId) as MaxT
        on MaxT.GrpId = T.GrpId and T.TimeStmp = MaxT.TimeStmp

SQL SELECT DISTINCT来自组的最新行

2 个答案: