Find the Supplier number for those suppliers who supply every part - mysql

Question

I have the following tables:
Suppliers(Sno, Sname, Address)
Parts(Pno, Pname, Colour)
Catalogue(Sno, Pno, Price)
and I want to find the Sno of the suppliers who supply every part.
So far, I've written this:
SELECT s.sname
FROM suppliers s JOIN catalogue c
USING s.sno
Now how do I write the part "suppliers that supply every part"?
I was thinking about having the count(*) from parts = count(pno) for each supplier Sno. Could someone please give me a hint/write the first part of the equality?
Thanks!

Answer 1

SELECT s.sname
FROM suppliers s
INNER JOIN catalogue c
ON s.Sno = c.Sno
GROUP BY s.sname
HAVING COUNT(c.Pno) = (SELECT COUNT(Pno) FROM Parts)

Answer 2

You're close. You need to add a group by/having clause with a subquery:
group by s.sname having count(*) = (select count(*) from catalogue)

Answer 3

Off the top of my head, you could write
SELECT s.Sno
FROM suppliers s
WHERE NOT EXISTS (
SELECT p.Pno
FROM parts p
WHERE NOT EXISTS (
SELECT c.*
FROM catalogue c
WHERE c.Pno = P.Pno
AND c.Sno = S.Sno
)
)
i.e. supplier where not exists (part that we don't supply), for a solution avoiding counts. No idea if this would be more or less efficient than the counts.

Answer 4

SELECT s.Sno, s.Sname
FROM Suppliers s
CROSS JOIN Parts p
LEFT JOIN Catalogue c ON s.Sno = c.Sno AND p.Pno = c.Pno
GROUP BY s.Sno, s.Sname
HAVING COUNT(*) = COUNT(c.Pno)

Answer 5

Try this:
alter proc clr
#c char(10),
#pno int output
as
begin
declare #f int
if exists(select p# from p where colour=#c)
begin
select #pno=p# from p where colour=#c
--set #f=1
end
-- else
-- set #f=0
-- return #f
end
--clr 'red',2
select p# from p where colour='red'
alter proc prcs
#c char(20)
as
begin
declare #pno numeric(2)
declare #f int
exec #f=clr #c,#pno output
--if #f=1
-- begin
select #pno
select s# from sp where p#=#pno
--set #i=1
-- end
--set #i=0
--return #i
end
prcs 'red'
select * from sp
select * from p,sp where p.p#=sp.p# and colour='red'
alter proc prcj
#c char(10)
as
begin
declare #i int
exec #i=prcs #c
if #i=1
begin
print'list of supplier'
select sname from s
where s#=#c
end
else
print'this record is not found'
end