T-SQL: Selecting Column Based on MAX(Other Column)

Question

I\'m hoping there\'s a simple way to do this without using a sub-query:

Scenario: You have \"TableA\" with columns \"Key\", \"SubKey\", and \"Value\". I need to ge

Answer 1

OMG Ponie's ROW_NUMBER method is the one that will work best in all scenarios as it will not fail in the event of having two MAX values with the same amount returning more records than expected and breaking a possible insert you might have being fed by that recordset.

One thing that is missing is how to do it in the event of having to return the subkey associated to each max value, when there are also multiple keys. Simply join your summary table with a MIN and GROUP "itself" and off you go.

WITH summary AS (
  SELECT t.*,
         ROW_NUMBER() OVER(ORDER BY t.subkey DESC) AS rank
    FROM TABLE t
   WHERE t.key = 1)
SELECT s.*
  FROM summary s
  join  (select key, min(rank) as rank
        from summary
        group by key) sMAX
        on s.key = sMAX.key and r.rank = sMAX.rank