如何找到每天最新日期时间的最新日期时间

Question

我在同一天有多行，我想获得过去五天当天的最新日期时间。

id username date
1 prashant  2013-10-09 05:25:46.000
2 rohit     2013-10-09 05:26:40.000
3 sam       2013-10-09 05:33:53.000
4 sohan     2013-10-09 05:26:15.000
5 mohan     2013-10-09 05:37:34.000

Answer 1

SELECT id,name,MAX([date])
FROM tableName
WHERE DATEDIFF(day,[date],GETDATE()) <= 5
GROUP BY id,name

Answer 2

试试这个

Select ID,
       Name,
       Date 
From Table1 
where Date 
  IN ( -- we are selecting the latest date for each day
      SELECT  MAX([date])Date
      FROM Table1 
      GROUP BY DATEPART(dd, [date]) 
      )

FIDDLE DEMO

如果您只想获取过去五天的记录，请使用此

Select ID,
       Name,
       Date 
From Table1 
where Date 
  IN ( -- we are selecting the latest date for each day
      SELECT  MAX([date])Date
      FROM Table1 
      WHERE DATEDIFF(day,[date],GETDATE()) <= 5
      GROUP BY DATEPART(dd, [date]) 
      )

FIDDLE DEMO

Answer 3

CREATE TABLE UserDate (
    id INT NOT NULL IDENTITY CONSTRAINT PK_UserDate PRIMARY KEY CLUSTERED
    ,username nvarchar(50) NOT NULL
    ,dt datetime
)

INSERT INTO UserDate (username, dt)
VALUES 
 ('usr1','2013-10-07 05:25:46.000')
,('usr2','2013-10-08 05:26:40.000')
,('usr3','2013-10-08 05:33:53.000')
,('usr4','2013-10-09 05:26:15.000')
,('usr5','2013-10-09 05:37:34.000')
,('usr6','2013-10-10 05:25:46.000')
,('usr7','2013-10-10 05:26:40.000')
,('usr8','2013-10-11 05:33:53.000')
,('usr9','2013-10-12 05:26:15.000')
,('usr10','2013-10-12 05:37:34.000')

SELECT * FROM UserDate

;With Last5 as (
SELECT 
    id,
    username,
    dt,
    DENSE_RANK() OVER (ORDER BY CAST(dt as Date) DESC) OrderByDay,
    ROW_NUMBER() OVER (PARTITION BY CAST(dt as Date) ORDER BY dt DESC) OrderByTime
FROM UserDate
)

SELECT * 
FROM Last5
WHERE OrderByDay <= 5
    and OrderByTime = 1
ORDER BY OrderByDay 
GO