If you write SQL, you might be interested in a recent article that I wrote about a subtle issue involving the merging of subqueries in the FROM clause of a SQL statement:
Chris Date found the issue interesting, and was kind enough to write a response:
Chris’s article is enlightening and well worth a read.
select lname,fname from employee where e_no in(select e_no from works_on where p_no=(select * from project))