Sua pergunta está meio confusa. Parece um simples
JOIN Deveria trabalhar:SELECT s.group_id
FROM stuff s
INNER JOIN something so ON s.group_id = so.group_id
WHERE s.member_id = 11 AND
so.some_id = 7
JOIN Deveria trabalhar:SELECT s.group_id
FROM stuff s
INNER JOIN something so ON s.group_id = so.group_id
WHERE s.member_id = 11 AND
so.some_id = 7
