How many different campuses are there?
select count(*) from campuses
How many degrees are granted in each campus over all years?
select t1.campus, sum(t2.degrees) from campuses as t1 join degrees as t2 on t1.id = t2.campus group by t1.campus
How about between 1998 and 2002?
select t1.campus, sum(t2.degrees) from campuses as t1 join degrees as t2 on t1.id = t2.campus where t2.year >= 1998 and t2.year <= 2002 group by t1.campus