SQL基于日期的不同行创建了行

Question

我有以下数据。

我需要查询数据，以便我只获得以下记录。

我需要基于DateApplication的唯一记录。如下所示。

有人可以告诉我如何在SQL Server 2008中执行此操作吗？

Answer 1

您可以在此处使用row_number()功能：

select
    name,
    email,
    dateapplication,
    description
from
(
    select *, row_number() over (partition by email order by dateapplication desc) as row_num
    from YourTable
)a
where row_num = 1

Answer 2

SELECT Name, email, MAX(DateApplication) As DateApplication, 
  (SELECT TOP 1 description
  FROM tbl As tbl1 
  where tbl1.Email = tbl.Email AND tbl1.DateApplication = MAX(tbl.DateApplication))
  ) As description
from tbl
GROUP BY Name, email

Answer 3

皮肤猫的方法不止一种，但通常情况下，你有一个子查询返回每个名字及其最新日期，然后用原始表格加入。

使用WITH语句

;WITH q AS (
  SELECT  Name, DateApplication = MAX(DateApplication)
  FROM    YourData
  GROUP BY
          Name
)
SELECT  Name
        , Email
        , DateApplication
        , Description
FROM    YourTable yt
        INNER JOIN q ON q.Name = yt.Name
                        AND q.DateApplication = yt.DateApplication

---

使用内部联接

SELECT  Name
        , Email
        , DateApplication
        , Description
FROM    YourTable yt
        INNER JOIN (
          SELECT  Name, DateApplication = MAX(DateApplication)
          FROM    YourData
          GROUP BY
                  Name
        ) q ON q.Name = yt.Name
               AND q.DateApplication = yt.DateApplication

---

请注意，在每个示例中，我都假设组合Name, DateApplication是唯一的。

Answer 4

你可以试试这个

SELECT Name, Email, DateApplication, Description
FROM ( SELECT ROW_NUMBER() OVER (PARTITION BY Name ORDER BY DateApplication DESC) RowNumber,
              Name, Email, DateApplication, Description
       FROM YourTableName)
WHERE RowNumber = 1

希望这有帮助

Answer 5

假设您想要最后一个条目，您可以这样做：

SELECT t1.Name, t1.Email, t1.DateApplication, t1.Description
FROM tablename t1
WHERE t1.DateApplication = 
      (SELECT MAX(t2.DateApplication)
       FROM tablename t2
       WHERE t2.Name = t1.Name AND t2.Email = t1.Email)