Return row with the max value of one column per group [duplicate]

Answer 1

You're on the right track using analytic functions. But you probably want something like this with the rank function

SELECT *
  FROM (SELECT a.*,
               rank() over (partition by id order by round desc) rnk
          FROM scores
         WHERE id IN (1,2,3))
 WHERE rnk = 1

If there can be ties (rows that have the same id and round) you may want to use the row_number analytic function instead of rank-- that will arbitrarily pick one of the two tied rows to have a rnk of 1 rather than returning both as rank would.

If you wanted to use the MAX analytic function, you could also do something like

SELECT *
  FROM (SELECT a.*,
               MAX(round) OVER (partition by id) max_round
          FROM scores
         WHERE id IN (1,2,3))
 WHERE round = max_round