Use only the operators discussed in class (select, project,
Cartesian product, join, union, intersection, set difference and
renaming). Type your answers.
The following database schema is given:
ATHLETE(name,age,height,weight,country)
RACE(id,location,date,time-start,distance)
COMPETES(aname,rid,time,position)
where ATHLETE has information about runners (their name, age,
height, weight, and nationality); RACE has information about races
(id, location, date when it’s held, time it starts, and distance
ran); and COMPETES keeps track of which runners run on with race,
the time it took them to complete the race,...