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

You could do something like this.

SELECT t1.ticket_id, 
       t1.assignment,
       t2.manager_name,
       t2.user
  FROM table1 t1
       LEFT OUTER JOIN (SELECT manager_name,
                               assignment_group,
                               user,
                               row_number() over (partition by assignment_group
                                                    --order by <>
                                                 ) rnk
                          FROM table2) t2
                     ON (    t1.assignment = t2.assignment_group
                         AND t2.rnk = 1 )

This partitions the data in table2 by assignment_group and then arbitrarily ranks them to pull one arbitrary row per assignment_group. If you care which row is returned (or if you want to make the row returned deterministic) you could add an ORDER BY clause to the analytic function.