Find the Supplier number for those suppliers who supply every part

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 thin开发者_如何学Cking 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!

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)

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)

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.

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)

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