SQL查询根据最新日期为每个成员获取1条最新记录

Question

我有一个像这样的数据库：

---------------------------------------------------
| MemberID | IntrCode | InstruReply | CreatedDate |  ...other 2 more columns
---------------------------------------------------
| 6        | 1        | Activated   | 26 FEB 2014 |
| 7        | 2        | Cancelled   | 25 FEB 2014 |
| 6        | 2        | Cancelled   | 15 FEB 2014 |
| 7        | 1        | Activated   | 03 FEB 2014 |
---------------------------------------------------

现在基于CreatedDate和instCode ，我需要一个查询，该查询基于instCode作为参数返回如下结果。

当@IntrCode = 1 ，我只需要最新的（ CreatedDate ）活动的MemberID 。

PS：请注意，成员7在检查最新日期（CreatedDate）时被取消。

输出量

---------------------------------------------------
| MemberID | IntrCode | InstruReply | CreatedDate |
---------------------------------------------------
| 6        | 1        | Activated   | 26 FEB 2014 |
---------------------------------------------------

我写了下面的查询，但无法显示其他列。（感谢您的帮助）

SELECT MemberID, MAX(CreatedDate) AS LatestDate FROM MyTable GROUP BY MemberID

Answer 1

您可以使用CTE和ROW_NUMBER函数 ：

With CTE As
(
    SELECT t.*, 
           RN = ROW_NUMBER()OVER(PARTITION BY MemberID Order By CreatedDate DESC)
    FROM MyTable t
    WHERE IntrCode = @IntrCode
)
SELECT MemberID, IntrCode, InstruReply, CreatedDate
FROM CTE
WHERE RN = 1

演示

Answer 2

尝试这个

方法1：

SELECT * FROM
(
  SELECT *,ROW_NUMBER()OVER(PARTITION BY MemberID Order By CreatedDate DESC) RN
  FROM MyTable WHERE InstruReply = 'Activated' AND IntrCode = @IntrCode
) AS T
WHERE RN = 1

方法2：

 SELECT * FROM
 (
   Select MemberID,max(CreatedDate) as LatestDate from MyTable group by MemberID
 ) As s INNER Join MyTable T ON T.MemberID = S.MemberID AND T.CreatedDate = s.LatestDate
 WHere T.InstruReply = 'Activated' T.IntrCode = @IntrCode

小提琴演示

输出量

---------------------------------------------------
| MemberID | IntrCode | InstruReply | CreatedDate |
---------------------------------------------------
| 6        | 1        | Activated   | 26 FEB 2014 |
---------------------------------------------------

Answer 3

这样，您可以为每个成员选择具有最新日期的整行。

SELECT * FROM MyTable t1
WHERE NOT EXISTS (SELECT * 
                  FROM MyTable t2 
                  WHERE t2.CreatedDate > t1.CreatedDate
                  AND t1.MemberID = t2.MemberID)
AND IntrCode = @IntrCode

Answer 4

;with TempData as (Select MemberId, IntrCode   ,InstruReply,CreatedDate  , MemberCount =ROW_NUMBER()
                over(PARTITION By MemberId Order By CreatedDate desc)
                From MyTable 
                )

Select *
From TempData
Where MemberCount =1

Answer 5

您编写的查询只是缺少WHERE子句，它将帮助您过滤所需的数据：

SELECT MemberID, MAX(CreatedDate) AS LatestDate
FROM MyTable
WHERE IntrCode = @IntrCode
  AND InstruReply = 'Activated'
GROUP BY MemberID