Thank you for your response!

I was actually thinking about doing the query like this, the problem is that this is an entry level class, and we haven't been taught how to do that.

I found this piece of code that does roughly what I want, do you think I could change this around and get it to work for my query?

-- Get part numbers for each part which is

-- supplied to all projects in London

P is Part table, J is Project table, SPJ is supplier part for project

SELECT pnum FROM P WHERE NOT EXISTS ( SELECT * FROM J WHERE city = 'London' AND NOT EXISTS ( SELECT * FROM SPJ WHERE spj.pnum = p.pnum AND spj.jnum= j.jnum));