0. The following integrity constraints MUST be implemented:

   1. When a record about a tour operator is removed from the database, the records about Airlines associated with this tour operator must also be removed from the database.

   2. When a record about a tour operators representative who supervised other representatives is removed from the database, the records about subordinate representatives must remain in the database.

   3. Domain of attribute Category (Room entity set) contains only three values: standard, luxury and executive.

   4. Domain of attribute Fee (Service entity set) contains numbers between 0 and 200.

   5. Domain of attribute Nbed (Room entity set) contains integer numbers 1, 2, and 3.

Website Category Title Bnum SID Fee Aname BView Phone Building Service Airline V N Has Sdate Deals Is_booked Rnum Nbed 1 TOID 1 Room VID Vdate Tour Operator Cname Category 1 Phone Is_accommodated Visit Mtype S Employs L GID K 1 Is_served Gname 1 Rname Guest RID Phone Address Restaurant 1 Q Representative Is_assigned Theme Principal Regular RestID Rtype Rname Credit Card Status Y Reports_to Website Category Title Bnum SID Fee Aname BView Phone Building Service Airline V N Has Sdate Deals Is_booked Rnum Nbed 1 TOID 1 Room VID Vdate Tour Operator Cname Category 1 Phone Is_accommodated Visit Mtype S Employs L GID K 1 Is_served Gname 1 Rname Guest RID Phone Address Restaurant 1 Q Representative Is_assigned Theme Principal Regular RestID Rtype Rname Credit Card Status Y Reports_to