Question

我的数据结构与Select only last value of date?相同，但我需要获取每个日期的值，我标记它们。 Feroc问题的解决方案是仅提供最后日期。

localName Date_Time                 RH  
BAG012    2014-10-09 17:17:58.000   16  <--     
BAG012    2014-10-09 17:13:28.000   16  
BAG012    2014-10-09 17:12:23.000   16  
BAG012    2014-10-09 16:52:54.000   16  
BAG012    2014-10-08 05:14:56.000   16  <--         
BAG012    2014-10-08 04:45:31.000   16  
BAG012    2014-10-08 04:44:08.000   16  
SAG165    2014-10-28 11:22:14.000   698 <--         
SAG165    2014-10-28 11:09:14.000   698     
SAG165    2014-10-28 10:53:18.000   698     
SAG165    2014-10-27 19:30:14.000   693 <--         
SAG165    2014-10-27 19:14:51.000   693     
SAG165    2014-10-27 19:13:56.000   693

这是我正在使用的代码：

WITH CTE AS
(
   SELECT LTRIM(localName) as localName, CAST(year(Date_Time) as varchar)+'-'+CAST(month(Date_Time) as varchar)+'-'+CAST(day(Date_Time) as varchar) as date_time, RH, tank, mode,
     RN = ROW_NUMBER() OVER (PARTITION BY localName ORDER BY Date_Time DESC)
   FROM dbo.SMCData
)

SELECT DISTINCT Date_Time, localName, RH, tank, mode
FROM CTE
WHERE RN = 1 
order by LocalName asc

由于日期时间也包括时间，我试图删除时间并只保留日期。
尝试使用DISTINCT Date_Time

以上两种情况均未对结果进行任何更改。

解答：谢谢大家，以下对我有用：

WITH CTE AS
(
   SELECT localName, Date_Time, RH,
     RN = ROW_NUMBER() OVER (PARTITION BY localName, CAST(Date_Time AS date) ORDER BY Date_Time DESC)
   FROM dbo.TableName
)
SELECT localName, Date_Time, RH
FROM CTE
WHERE RN = 1
ORDER BY localName, Date_Time;

Answer 1

WITH CTE AS
(
   SELECT localName, Date_Time, RH,
     RN = ROW_NUMBER() OVER (PARTITION BY localName, CAST(Date_Time AS date) ORDER BY Date_Time DESC)
   FROM dbo.TableName
)
SELECT localName, Date_Time, RH
FROM CTE
WHERE RN = 1
ORDER BY localName, Date_Time;

Answer 2

使用select distinct：

SELECT DISTINCT date
FROM table_name

它将为您提供每个日期

Answer 3

SELECT DISTINCT localName, Date , RH
FROM table_name

这应该给出唯一的日期和RH值以及相应的localName。

Answer 4

按日期分组：

SELECT localName, MAX(date_time) AS max_date_time, MAX(rh) AS max_rh
FROM your_table
GROUP BY localName, CAST(date_time AS date)

这将为您提供每个本地名称的最后日期。

Sample SQL Fiddle

输出：

localName  max_date_time           max_rh
---------- ----------------------- -----------
BAG012     2014-10-08 05:14:56.000 16
BAG012     2014-10-09 17:17:58.000 16
SAG165     2014-10-27 19:30:14.000 693
SAG165     2014-10-28 11:22:14.000 698

按日期选择值

4 个答案: