SELECT rows with unique values in two columns

Question

I have a table like this:

id          col1 col2        
----------- ---- ----------- 
1           A    5
2           A    6
3           B    5
4           B          


        

Answer 1

SELECT  id, col1, col2
FROM    ( SELECT    * ,
                    ROW_NUMBER() OVER ( PARTITION BY col2 ORDER BY col2 ) Row#
          FROM      #t
        ) x
WHERE   x.Row# = 1