SSMS：如何只返回每个月/年的最后一行而不是每一行的值？

Question

我正在使用的代码返回月/年中的所有日期，但我只希望它返回最后一个日期行而不是所有每日行。

这是我正在使用的代码。

;WITH OIL_INDEX AS (
    SELECT PRODUCT_SYMBOL
    ,CONTRACT_MONTH
    ,CONTRACT_YEAR
    ,CONTRACT_DETAIL
    ,TRADEDATE
    ,SETTLE
    ,AVG(SETTLE) OVER (
            PARTITION BY CONTRACT_DETAIL, YEAR(TRADEDATE), MONTH(TRADEDATE)
            ORDER BY TRADEDATE 
            ROWS BETWEEN 29 PRECEDING and CURRENT ROW
        ) AS MA30
    ,YEAR(TRADEDATE) AS TRADEYEAR
    ,MONTH(TRADEDATE) AS TRADEMONTH
    ,DAY(TRADEDATE) AS TRADEDAY
    ,row_number() OVER(
     PARTITION BY CONTRACT_DETAIL, TRADEDATE
      ORDER BY TRADEDATE DESC) AS RowNum
     FROM Pricing.dbo.MasterReport$

)

SELECT PRODUCT_SYMBOL
    ,CONTRACT_MONTH
    ,CONTRACT_YEAR
    ,CONTRACT_DETAIL
    ,TRADEDATE
    ,TRADEYEAR
    ,TRADEMONTH
    ,TRADEDAY
    ,SETTLE
    ,MA30
    FROM OIL_INDEX
    WHERE RowNum = 1 AND PRODUCT_SYMBOL
    IN ('CL','CY','WJ')
    ORDER BY PRODUCT_SYMBOL ASC, CONTRACT_DETAIL ASC,TRADEYEAR ASC, TRADEMONTH ASC, TRADEDAY ASC

这是给出的结果。

这是我想要的。

Answer 1

我认为你只需要修改窗口函数的PARTITION BY子句：

前：

ROW_NUMBER() OVER(
    PARTITION BY CONTRACT_DETAIL, TRADEDATE
    ORDER BY TRADEDATE DESC
) AS RowNum

后：

ROW_NUMBER() OVER(
    PARTITION BY CONTRACT_DETAIL, YEAR(TRADEDATE), MONTH(TRADEDATE)
    ORDER BY TRADEDATE DESC
) AS RowNum

基本原理：您的分区子句为每个不同的(CONTRACT_DETAIL, TRADEDATE )元组创建一个新组； 这是生成很多组的利利，每个组可能只有一个记录。 相反，您希望按合同和月份进行分区，然后按交易日期对每个组中的记录进行排名。