What are the locations of performances?
select location from performance
How about locations of performances with less than 1000 attendees?
select location from performance where attendance < 1000
What about those with more than 2000 attendees?
select location from performance where attendance > 2000
Show the locations that have both performances with more than 2000 attendees and performances with less than 1000 attendees.
select location from performance where attendance > 2000 intersect select location from performance where attendance < 1000