Question

我有两张桌子

TableA有一个实体的历史状态列表。这些也可以颠倒，如果反转，则需要忽略该行。

EntityID  |  StatusDate  |  Status  |  IsReversed
-------------------------------------------------
1         |  2014-01-15  |  A       |  NULL
1         |  2014-06-17  |  B       |  Y
1         |  2015-01-19  |  C       |  NULL

TableB有一个实体的维护日期列表

EntityID  |  MaintDate
-----------------------
1         |  2014-02-20
1         |  2014-03-30
1         |  2015-11-22

我想提供一份维护日期清单，其中还列出了维护日期的实体状态。

我已经了解了如何检索单个日期的个人状态

SELECT TOP 1 
  Status
FROM
  TableA
WHERE
  StatusDate < '2014-03-30' AND IsReversed != 'Y'
ORDER BY 
  StatusDate DESC

但我无法弄清楚如何将其整合到查询中以检索每个日期的状态。

提前感谢您的帮助！

以下是实际查询#SITELIST是TableB，“LNSP_UAT.dbo.INSTALLSTATUS”是TableA：

SELECT DISTINCT
    I.INSTALL [INSTALL]
    ,RD.GBR$CDATE [ENDDATE]
    ,RD.GBR$PDATE [STARTDATE]

INTO #SITELIST

FROM
    LNSP_UAT.dbo.INSTALL I
    LEFT JOIN LNSP_UAT.dbo.GBBILLREG RG ON RG.GBB$INSTALL = I.INSTALL
    LEFT JOIN LNSP_UAT.dbo.GBREGISTER RD ON RD.GBR$BREGKEY = RG.GBB$REGKEY AND RD.GBR$STATUS = 25 AND RD.GBR$CTYPE IN ('N','D','A','G','S')


SELECT
    SL.INSTALL
    ,SL.STARTDATE
    ,SL.ENDDATE
    ,ST.ISSTATUS

FROM
    #SITELIST SL
    OUTER APPLY (
        SELECT TOP 1
            ST.ISSTATUS
        FROM
            LNSP_UAT.dbo.INSTALLSTATUS ST
        WHERE
            ST.ISINSTALL = SL.INSTALL
            AND ST.ISREVERSE != 'Y'
            AND ST.ISEFFDATE <= SL.STARTDATE
        ORDER BY
            ISEFFDATE DESC
    ) A
    ORDER BY ENDDATE DESC


DROP TABLE #SITELIST

Answer 1

您要找的是APPLY：

SELECT
    b.*, a.Status
FROM TableB b
OUTER APPLY (
    SELECT TOP 1 Status
    FROM TableA
    WHERE
        EntityID = b.EntityID
        AND IsReversed != 'Y'
        AND StatusDate <= b.MaintDate
   ORDER BY StatusDate DESC
) a

Answer 2

SELECT
    b.*, 
    (SELECT TOP 1 
        Status
    FROM
      TableA
    WHERE
      EntityID = b.EntityID
      AND IsReversed != 'Y' AND StatusDate < b.MaintDate 
    ORDER BY 
      StatusDate DESC) as status
FROM TableB b

提取日期列表的历史状态

2 个答案: