Disqus - Latest Comments for elai

Re: Relational algebra: division in sql

elai — Thu, 17 Apr 2008 02:25:36 -0000

Yas,

Thanks for your postings and comments regarding Relational Algebra: division in sql!

elai

Re: Relational algebra: division in sql

elai — Thu, 17 Apr 2008 02:09:48 -0000

How about these two sets of queries for division in the case of having all red parts:

select distinct sid
from catalog c, parts p
where c.pid = p.pid and color = 'Red'
group by sid
having count(distinct c.pid) =
(select count(distinct pid)
from parts
where color = 'Red');

select distinct sid
from catalog c1
where not exists (
(select pid
from parts
where color = 'Red')
minus
(slect pid
from catalog c2
where c1.sid = c2.sid));

Re: Relational algebra: division in sql

elai — Wed, 16 Apr 2008 07:06:45 -0000

How about these two sets of queries for division:

select distinct sid
from catalog c, parts p
where c.pid = p.pid
group by sid
having count(distinct c.pid) =
(select count(distinct pid)
from parts);

select distinct sid
from catalog c1
where not exists (
(select pid
from parts)
minus
(slect pid
from catalog c2
where c1.sid = c2.sid));