从 MS Access 中的子查询中检索多个值

debugcn 发表于 Dev

ChemEnger

我有一张表 (SPG)，上面有个人 (DonorID)、捐赠日期 (DonateDate) 和捐赠地点 (Center)。我想找到捐赠的日期和地点（简单），然后是下一次捐赠的日期和地点，以及两个日期之间的差距。

我使用了一个 SELECT 子查询，它给了我下一个日期（NextDate），但我无法获得匹配的中心：

SELECT SPG.DonorID,
       SPG.DonateDate,
       SPG.Center AS Center1,
       (SELECT Min(DonateDate) as MinDate
          FROM SPG As A
         WHERE SPG.DonorID = A.DonorID
           AND A.DonateDate > SPG.DonateDate) AS NextDate,
       [NextDate]-[DonateDate] AS Gap
  FROM SPG
 GROUP BY SPG.DonorID, SPG.DonateDate, SPG.Center
HAVING ((((SELECT Min(DonateDate) as MinDate
             FROM SPG As A
            WHERE SPG.DonorID = A.DonorID
              AND A.DonateDate > SPG.DonateDate))<>""))
 ORDER BY SPG.DonorID, SPG.DonateDate;

我有一个不同的 INNER JOIN 查询，它为我提供了中心，但它返回所有未来的捐赠，而不仅仅是下一个：

SELECT A.DonorID,
       A.DonateDate,
       A.Center,
       Min(B.DonateDate) AS NextDate, 
       B.Center,
       [B].[DonateDate]-[A].[DonateDate] AS Gap
  FROM SPG AS A INNER JOIN SPG AS B ON A.DonorID = B.DonorID
 WHERE B.DonateDate > A.DonateDate
 GROUP BY A.DonorID,
          A.DonateDate,
          A.Center,
          B.Center,
          B.DonateDate-A.DonateDate;

基本上，我似乎无法将子查询中的 Min() 命令与从 JOIN 返回多个字段结合起来。

（请原谅不同的符号 - 大量复制和粘贴试用代码）

李麦克

这里的一位 SQL 大神可能知道一种更简洁的方法，但这就是我目前所拥有的：

select 
    s1.donorid,
    s1.donatedate,
    s1.center as center1, 
    (
        select min(s2.donatedate)
        from spg s2
        where s1.donatedate < s2.donatedate and s1.donorid = s2.donorid
    ) as nextdate, 
    (
        select s2.center
        from spg s2
        where 
        s1.donorid = s2.donorid and
        s2.donatedate = 
        (
            select min(s3.donatedate)
            from spg s3
            where s1.donatedate < s3.donatedate and s1.donorid = s3.donorid
        )
    ) as center2, 
    nextdate - s1.donatedate as gap
from
    spg s1
order by
    s1.donorid,
    s1.donatedate

如果你只关注那些有“下一个”捐赠日期的记录，也许：

select 
    s1.donorid,
    s1.donatedate,
    s1.center as center1, 
    (
        select min(s2.donatedate)
        from spg s2
        where s1.donatedate < s2.donatedate and s1.donorid = s2.donorid
    ) as nextdate, 
    (
        select s2.center
        from spg s2
        where 
        s1.donorid = s2.donorid and
        s2.donatedate = 
        (
            select min(s3.donatedate)
            from spg s3
            where s1.donatedate < s3.donatedate and s1.donorid = s3.donorid
        )
    ) as center2, 
    nextdate - s1.donatedate as gap
from
    spg s1
where exists 
    (select 1 from spg s2 where s1.donorid = s2.donorid and s1.donatedate < s2.donatedate)
order by
    s1.donorid,
    s1.donatedate

我听说你喜欢相关的子查询...

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