SELECT COALESCE(New_a.id,New_b.id) id ,New_a.name,New_b.code
FROM (SELECT id,name
FROM a a_1
WHERE NOT EXISTS(SELECT *
FROM a a_2
WHERE a_1.id=a_2.id AND a_1.dt<a_2.dt)) New_a
FULL JOIN
(SELECT id,code
FROM b b_1
WHERE NOT EXISTS(SELECT *
FROM b b_2
WHERE b_1.id=b_2.id AND b_1.dt<b_2.dt)) New_b
ON New_a.id=New_b.id
ORDER BY id