SELECT
    t1.a_id,
    t1. NAME,
    t2.b_id,
    t2.create_time
FROM
    a AS t1
LEFT OUTER JOIN b AS t2 ON t1.a_id = t2.a_id
WHERE
    t2.b_id = (
        SELECT
            b.b_id
        FROM
            b
        WHERE
            a_id = t1.a_id
        ORDER BY
            create_time ASC
        LIMIT 1
    );