如何使用存储过程仅获取一条最新记录

Question

我有大约7条记录，其中两条记录具有相同的用户但具有不同的MailLevel＆amp; SentDate状态，所以我只想获得该特定用户的最新记录。任何人都可以帮助我如何执行Sql查询

请查看下面的图片以便清楚了解

http://s16.postimg.org/res5p5gmd/TESTPAGE.png

Answer 1

如果您只想使用此特定用户的最新记录，则可以使用：

CREATE PROCEDURE SelectLatestRecored

@UserId int

AS

SELECT TOP 1 [Col1], [Col2] ,[Col3], [SendDate], [MailLevel]
FROM [YourTable]
ORDER BY [SentDate] DESC 
WHERE [UserId] = @UserId

GO

如果您想要每个用户的最新记录：

CREATE PROCEDURE SelectLatestRecoreds

AS

SELECT
  ROW_NUMBER() OVER (PARTITION BY [UserId] ORDER BY [SendDate] DESC) AS [RowNum],     
  [Col1], [Col2] ,[Col3], [SendDate], [MailLevel]

FROM [YourTable]
WHERE [RowNum] = 1

GO

Answer 2

子选择在主选择

上添加行号列和where子句的表

SELECT *  
FROM (
    SELECT MyTable.*, ROW_NUMBER() OVER (Partition BY UserId ORDER BY MailLevel DESC, SentDate DESC) AS R 
    FROM MyTable ) AS T 
WHERE T.R=1

Answer 3

根据我对具有2次不同邮件级别和发送日期的条目的用户记录的理解，它将选择最近的记录以及其他记录。

  select *
  from
   (
     SELECT
     ROW_NUMBER() OVER (PARTITION BY [creatorName] ORDER BY [SendDate] DESC)
     AS [RowNum],     
     *
     FROM [YourTable]
   )base
  WHERE [RowNum] = 1