Getting the First and Last Row Using ROW_NUMBER and PARTITION BY

Question

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:

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

Vamsi Prabhala · Accepted Answer · 2017-08-08T15:34:18.177

This can be done using window functions min and max.

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

Example

Edit: Based on the comments

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.

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

Note that this query will work only if `value` grow in time. If we change `value` from 1 to 10 in the first row of OPs example - this query will produce wrong results. — gofr1, Jul 21 '16 at 14:34
@gofr1 yes. what you probably want to use is `last_value(value) over (partition by name order by timestamp)` — Chitharanjan Das, Jul 21 '16 at 14:37

gofr1 · Answer 2 · 2016-07-21T14:35:44.687

You can use MIN and MAX functions + OUTER APPLY:

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:

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

score 1 · Answer 3 · answered Jul 21 '16 at 14:05

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.

This should be close:

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

score 1 · Answer 4 · answered Jul 21 '16 at 14:06

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

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

score 1 · Answer 5 · edited Jul 27 '16 at 07:42

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

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

score 0 · Answer 6 · answered Jul 21 '16 at 14:16

0

Think simple.

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

answered Jul 21 '16 at 14:16

neer

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Getting the First and Last Row Using ROW_NUMBER and PARTITION BY

Sample Input

Desired Output

Attempted Query

6 Answers6