Попробуйте это:
SELECT DISTINCT b.id
FROM (
SELECT id,
COUNT(1) cnt
FROM table_a
GROUP BY id
) a,
(
SELECT id,
COUNT(1) cnt
FROM table_a
WHERE CODE LIKE '%6'
GROUP BY id
)b
WHERE a.id = b.id
AND a.cnt = b.cnt
Альтернатива с использованием АНАЛИТИЧЕСКИХ функций:
SELECT DISTINCT id
FROM
(
SELECT id,
COUNT(1) OVER(PARTITION BY id) cnt,
SUM(CASE WHEN code LIKE '%6' THEN 1 ELSE 0 END) OVER(PARTITION BY id) sm
FROM table_a
)
WHERE cnt = sm