/* list the supplier number and supplier name for suppliers who DO NOT supply any parts USE subqueries*/
select snumber
from supplier
where not exists
(select *
	from spj
		where spj.snumber = supplier.snumber);
		
		
/* list the supplier number and supplier name for suppliers who DO NOT supply any parts USE subqueries*/
select snumber
from supplier
where snumber in /* you may use a NOT in and and omit the FALSE at the end */
(select *
	from spj
		where spj.snumber = supplier.snumber) = false;

select snumber
from supplier
where snumber in
(select snumber from spj) = false;

/* AAAAAAAAAAAAAAAAAA */

select distinct snumber
from spj as c 
where not exists 

(select *
 	from project as a cross join spj as b 
 	where c.snumber = b.snumber and not exists 
 
 	(select * 
     from spj
     	where b.snumber=spj.snumber and a.jnumber = spj.jnumber))