How do I limit the number of rows returned by this LEFT JOIN to one?

Question

So I think I\'ve seen a solution to this however they are all very complicated queries. I\'m in oracle 11g for reference.

What I have is a simple one to many join w

Answer 1

If oracle supports row number (partition by) you can create a sub query selecting where row equals 1.

SELECT * FROM table1
LEFT JOIN
(SELECT *
FROM   (SELECT *,
           ROW_NUMBER()
             OVER(PARTITION BY assignmentgroup ORDER BY assignmentgroup) AS Seq
    FROM  table2) a
WHERE  Seq = 1) v
ON assignmet = v.assignmentgroup