Question

I have a table like this

Col1   Col2  Mindate                        MaxDate 
A       B    12-04-2012 00:12:00:087        31-04-2012 00:00:01:001
C       D    01-01-2011                     30-01-2011 
A       B    09-05-2012                     27-05-2012
A       B    11-07-2012                     21-07-2012

I have only inserted datetime in first row but omitied in other rows for brevity, all date columns are datetime.

Assume that I have inserted the last records for A and B (Col1 and Col2 are combined key).
Now I want last record for A amd B based on the mindate which in above case should be

A       B    09-05-2012                     27-05-2012

I am trying the following query:

SELECT * FROM tbl WHERE Col1 ='A' AND Col2='B' AND ....

Answer 1

You can use ROW_NUMBER:

WITH CTE AS
(
   SELECT Col1, Col2, Mindate, MaxDate
    , RN = ROW_NUMBER() OVER (PARTITION BY Col1, Col2 ORDER BY Mindate DESC)
   FROM dbo.Tbl
   WHERE COL1='A' AND COL2='B'
)
SELECT Col1, Col2, Mindate, MaxDate
FROM CTE 
WHERE RN = 2

This would return the second last record according to Mindate and the given key.