SQL correct way of joining if the other parameter is null

Question

I have this code and its temporary tables so you can run it.

create table #student
(
    id int identity(1,1),
    firstname varchar(50),
    lastname varchar(50         


        

Answer 1

This

Select Q.id , Q.quiz_name ,S.firstname, S.lastname
from 
    #quiz Q                -- cross join, returns N*K results, do not use without 
    CROSS JOIN #student S  -- where condition that limits it - SAS solution is nicer!
where not exists (select 1 from #quiz_details where quiz_id = Q.id and student_id = S.id)

will give you

id  quiz_name                         firstname     lastname
1   NBA 50 Greatest Player Quiz       LeBron        James
2   NBA Top 10 3 point shooters       Stephen       Curry

---

Edit: changed code to explicit cross join rather then implicit, leaving both in here for comparison

SELECT #quiz Q, # student S           -- old implicit syntax - comma is easily missed

vs.

SELECT #quiz Q CROSS JOIN #student S  -- makes it clearer what is wanted