Select first record in a One-to-Many relation using left join

Question

I\'m trying to join two tables using a left-join. And the result set has to include only the first record from the \"right\" joined table.

Lets say I have two tables

Answer 1

In Oracle you can do:

WITH first_b AS (SELECT code, min(rowid) AS rid FROM b GROUP BY code)) 
SELECT a.code, a.emp_no, b.city, b.county
FROM a 
INNER JOIN first_b 
 ON first_b.code = a.code
INNER JOIN b
 ON b.rowid = first_b.rid