Attributes)(listed(separately(for(clarity(in(ER(diagram)(((Design)decisions:)(Airline,(airport,(and(aircraft(reflect(the(need(to(represent(these(different(objects(in(the(enterprise.((I(have(included(a(small(set(of(attributes(based(on(the(requirements((and(also(based(on(my(own(knowledge(of(the(data).((The(distance(between(two(airports(is(kept(in(the(“dist”(relationship(set.((The(fact(that(an(airline(has(an(airport(as(a(hub(is(in(the(“hub”(relationship(set.((Ownership(of(aircraft(by(airlines(is(in(the(“fleet”(relationship(set((see(below(for(more(detail(on(this).((I(have(gone(easy(on(constraints(here,(so(that(an(airline(does(not(necessarily(have(to(have(a(hub,(an(airport(does(not(have(to(be(a(hub,(we(do(not(need(to(know(the(distance(between(every(pair(of(airports,(and(aircraft(and(airlines(can(exist(without(being(related(to(airlines(or(aircraft((respectively).((Flights(are(stored(in(an(entity(set(wit h( oneHtoHmany,(total(participation(relationships(with(two(airports,(an(aircraft,(and(an(airline.((This(reflects(the(requirement(that(each(flight(be(scheduled(by(a(single(airline(on(a(single(aircraft(from(one(airport(to(another.((The(flight(entity(set(could’ve(alternatively(been(modeled(as(a(relationship(set(between(airlines,(airports,(aircraft,(and(fares;(I(chose(to(model(it(as(an(entity(set(because(that(prevents(some(redundancy:((since(there(can(be(several(different(fares(on(each(flight,(modeling(flights(as(relationship(sets(would(require(that(all(airports,(airlines,(and(aircraft(involved(in(the(flight(be(duplicated(in(the(data(for(each( sep
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