theory_exercise_8.md

Exercise 8

9. below

   1. Res = Proj_[eid] ( Sel_{[aname = 'Boeing 747']} ( Aircraft Join Certified ) )

   2. Res = Proj_[ename] ( Sel_{[aname = 'Boeing 747']} ( Aircraft Join_{[aid=aircraft]} ( Certified Join_{[employee=eid]}Employees ) ) )

   3. Res = Proj_[aid] ( Sel_{[cruisingRange>distance]} ( Aircraft Join Sel_{[to='New York' and from 'Los Angeles']} ( Flights ) ) )

   4. Tmp = Proj_{[flno, aid]} ( Sel_{[cruisingRange>distance]} ( Aircraft Join Flights ) )
      Res = Proj_[flno] ( Sel_{[salary>100 000]} ( Tmp Join Employees Join Certified ) )

   5. Tmp = Proj_{[cruisingDistance>3000]}