Join one to many and retrieve single result

Question

I have two tables, in PostgreSQL if that matters, with one to many relations. I need to join them so that for each \"one\" I only get single result from the \"many\" table. Not

Answer 1

PostgreSQL supports window function. Try this,

SELECT d.ID, d.NAME, d.DATE, d.CODE1, d.CODE2
FROM
(
  SELECT  a.ID, a.NAME, a.DATE,
          b.CODE1, b.CODE2,
          ROW_NUMBER() OVER(PARTITION BY a.ID ORDER BY b.SORT ASC, b.CODE2 DESC) AS ROWNUM
  FROM    TableA a
          INNER JOIN TableB b
            ON a.ID = b.ID
) d
WHERE d.RowNum = 1

SQLFiddle Demo