SELECT DISTINCT nomer_postavshika
FROM spj o1
WHERE NOT EXISTS (
                  SELECT nomer_detali
                  FROM spj o2
                  WHERE nomer_postavshika = 'S2'
                   AND NOT EXISTS (
                                    SELECT *
                                    FROM spj
                                    WHERE nomer_postavshika = o1.nomer_postavshika
                                      AND nomer_detali = o2.nomer_detali
                                   ) 
                 );