Sample Input

Name | Value | Timestamp
-----|-------|-----------------
One  | 1     | 2016-01-01 02:00
Two  | 3     | 2016-01-01 03:00
One  | 2     | 2016-01-02 02:00
Two  | 4     | 2016-01-03 04:00

Desired Output

Name | Value | EarliestTimestamp | LatestTimestamp
-----|-------|-------------------|-----------------
One  | 2     | 2016-01-01 02:00  | 2016-01-02 02:00
Two  | 4     | 2016-01-01 03:00  | 2016-01-03 04:00

Attempted Query

I am trying to use ROW_NUMBER() and PARTITION BY to get the latest Name and Value but I would also like the earliest and latest Timestamp value:

我正在尝试使用ROW_NUMBER()和PARTITION BY来获取最新的名称和值，但是我也希望获得最早和最新的时间戳值:

SELECT
    t.Name,
    t.Value,
    t.????????? AS EarliestTimestamp,
    t.Timestamp AS LatestTimestamp
FROM 
    (SELECT
        ROW_NUMBER() OVER (PARTITION BY Name ORDER BY TIMESTAMP DESC) AS RowNumber,
        Name,
        Value
        Timestamp) t
WHERE t.RowNumber = 1

6 个解决方案

#1

This can be done using window functions min and max.

这可以使用窗口函数min和max来完成。

select distinct name, 
min(timestamp) over(partition by name), max(timestamp) over(partition by name)
from tablename

Example

例子

Edit: Based on the comments

编辑:基于评论

select t.name,t.value,t1.earliest,t1.latest
from t 
join (select distinct name, 
      min(tm) over(partition by name) earliest, max(tm) over(partition by name) latest
      from t) t1 on t1.name = t.name and t1.latest = t.tm

Edit: Another approach is using the first_value window function, which would eliminate the need for a sub-query and join.

编辑:另一种方法是使用first_value窗口函数，这将消除子查询和连接的需要。

select distinct
name, 
first_value(value) over(partition by name order by timestamp desc) as latest_value,
min(tm) over(partition by name) earliest,
-- or first_value can be used 
-- first_value(timestamp) over(partition by name order by timestamp)
max(tm) over(partition by name) latest
-- or first_value can be used
-- first_value(timestamp) over(partition by name order by timestamp desc)
from t

#2

Use MIN(Timestamp) OVER (PARTITION BY Name) in addition to the ROW_NUMBER() column, like so:

除了ROW_NUMBER()列之外，在(按名称划分的分区)上使用MIN(时间戳)，如下所示:

SELECT
    t.Name,
    t.Value,
    t.EarliestTimestamp AS EarliestTimestamp,
    t.Timestamp AS LatestTimestamp
FROM 
    (SELECT
        ROW_NUMBER() OVER (PARTITION BY Name ORDER BY TIMESTAMP DESC) AS RowNumber,
        MIN(Timestamp) OVER (PARTITION BY Name) AS EarliestTimestamp,
        ^^
        Name,
        Value
        Timestamp) t
WHERE t.RowNumber = 1

#3

You can use MIN and MAX functions + OUTER APPLY:

你可以使用最小和最大值函数+外部应用:

SELECT  t.Name, 
        p.[Value],
        MIN(t.[Timestamp]) as EarliestTimestamp ,
        MAX(t.[Timestamp]) as LatestTimestamp
FROM Table1 t
OUTER APPLY (SELECT TOP 1 * FROM Table1 WHERE t.Name = Name ORDER BY [Timestamp] DESC) p
GROUP BY t.Name, p.[Value]

Output:

输出:

Name    Value   EarliestTimestamp   LatestTimestamp
One     2       2016-01-01 02:00    2016-01-02 02:00
Two     4       2016-01-01 03:00    2016-01-03 04:00

#4

If I'm understanding your question correctly, here's one option using the row_number function twice. Then to get them on the same row, you can use conditional aggregation.

如果我理解正确，这里有一个选项两次使用row_number函数。然后要将它们放在同一行上，可以使用条件聚合。

This should be close:

这应该是关闭:

SELECT
    t.Name,
    t.Value,
    max(case when t.minrn = 1 then t.timestamp end) AS EarliestTimestamp,
    max(case when t.maxrn = 1 then t.timestamp end) AS LatestTimestamp
FROM 
    (SELECT
        ROW_NUMBER() OVER (PARTITION BY Name ORDER BY TIMESTAMP) as minrn,
        ROW_NUMBER() OVER (PARTITION BY Name ORDER BY TIMESTAMP DESC) as maxrn,
        Name,
        Value
        Timestamp
     FROM YourTable) t
WHERE t.minrn = 1 or t.maxrn = 1
GROUP BY t.Name, t.Value

#5

Think simple.

认为简单。

select 
    t.Name, 
    MAX(t.Value), 
    MIN(t.Timestamp), 
    MAX(t.Timestamp) 
FROM 
    t
group by 
    t.Name

#6

If I understood your question, use the row_number() function as follows:

如果我理解您的问题，请使用row_number()函数如下:

SELECT  
    t.Name,  
    t.Value,  
    min(t.Timestamp) Over (Partition by name) As EarliestTimestamp,  
    t.Timestamp AS LatestTimestamp  
FROM   
    (SELECT ROW_NUMBER() OVER (PARTITION BY Name ORDER BY TIMESTAMP DESC) AS     RowNumber,  
        Name,  
        Value,  
        Timestamp) t  
WHERE t.RowNumber = 1  
Group By t.Name, t.Value, t.TimeStamp

#1