how to select only row with max sequence without using a subquery?

Question

I\'m trying to select only the row with the highest seq for each ID

ID  |  Seq   |  Age
-------------------
 A      1       20   
 A      2       30
 B               


        

Answer 1

Assuming SQL-Server ( >= 2005) or Oracle (10g?):

WITH CTE AS
( 
   SELECT
       ROW_NUMBER() OVER (PARTITION BY ID  ORDER BY Seq DESC) AS RN
       , ID, Age
   FROM 
       Persons
)
SELECT ID, Age 
FROM CTE
WHERE RN = 1

ROW_NUMBER returns the sequential number of a row within a partition of a result set.

Edit: works also in Oracle as you can see here: http://sqlfiddle.com/#!4/b7e79/2/0