Question

我有两个表，都有一个公共ID列。第二个表包含与第一个表中的ID列匹配的多个行，我需要从第二个表返回最新的条目。我的解决方案几乎是正确的，但它在所有ID列中返回单个值，而不是与该实际ID列对应的值。

正如您所看到的，它正在处理付款，因此只需要返回最近付款所涵盖的日期。

(SELECT TOP 1CONVERT(VARCHAR,MemberPayments.CoverFinishDay,105)
FROM
    Members LEFT JOIN MemberPayments
        ON Members.MemberID = MemberPayments.MemberID
        AND MemberPayments.CoverFinishDay = (
            SELECT MAX(CoverFinishDay)
            FROM MemberPayments
            WHERE Members.MemberID = MemberPayments.MemberID
        ))

任何想法为什么它会在所有人中返回一个值？

Answer 1

这是你在找什么？

;WITH LatestMemPayments AS
(
    SELECT   MemberID
            ,CoverFinishDay = MAX(CoverFinishDay)
    FROM    MemberPayments
    GROUP BY MemberID
)

SELECT *
FROM Members            ME
JOIN LatestMemPayments  MP  ON ME.MemberID = MP.MemberID

写为派生表而不是CTE;

SELECT *
FROM Members            ME
JOIN    (
            SELECT   MemberID
                    ,CoverFinishDay = MAX(CoverFinishDay)
            FROM    MemberPayments
            GROUP BY MemberID
        )               MP  ON ME.MemberID = MP.MemberID

可能是单个查询;

SELECT   ME.Col1
        ,ME.Col2
        ,CoverFinishDay = MAX(MP.CoverFinishDay)
FROM Members        ME
JOIN MemberPayments MP  ON ME.MemberID = MP.MemberID
GROUP BY ME.Col1
        ,ME.Col2

Answer 2

试试这个，它会在MemberPayments中找到最新数据的所有信息：

SELECT * 
FROM 
  Members
OUTER APPLY
(SELECT top 1 * 
 FROM 
   MemberPayments 
 WHERE 
   Members.MemberID = MemberPayments.MemberID 
 ORDER BY 
   CoverFinishDay DESC) x

如果您只需要最新日期：

SELECT m.MemberID, m.Field2, m.Field3, max(mp.CoverFinishDay) as LatestDate
FROM 
  Members m
LEFT JOIN
   MemberPayments mp
ON
   Members.MemberID = MemberPayments.MemberID 
GROUP BY m.MemberID, m.Field2, m.Field3

匹配两个ID列并从第二个表返回最近的条目

2 个答案: