Q2

This question is based on Sections 2, 3 and 4 of Block 2. It assesses your ability to transform a relational model into an E-R model. Figure 2 gives part of a relational representation of an engineering company in terms of staff, projects and machines. model Engineering Company domains StaffNumbers = {S0001... S9999} Projectlds = {P0001...P9999} Machinelds = {M000...M999} Names = String Descriptions = String Grades = {1...5} Dates = standard dates relation Staff StaffNo: StaffNumbers Name: Names Grade: Grades AppointmentDate: Dates primary key StaffNo relation Company Project Projectld: Projectlds StartDate: Dates EstimatedFinishDate: Dates Manager: StaffNumbers primary key Projectld alternate key Manager foreign key Manager references Staff constraint ((project Company Project over Projectld) difference (project WorksOn over Projectld)) is empty constraint ((project Company Project over Projectld) difference (project Machine over Projectld)) is empty relation Works On Projectld: Projectlds StaffNo: StaffNumbers primary key (Projectld, StaffNo) foreign key Projectld references Company Project foreign key StaffNo references Staff relation Machine Machineld: Machinelds Description: Descriptions Date OfLast Service: Dates Projectld: Projectlds primary key Machineld foreign key Projectld references Company Project relation Machine Training Machineld: Machinelds StaffNo: StaffNumbers Date OfTraining: Dates primary key (Machineld, StaffNo) foreign key Machineld references Machine foreign key StaffNo references Staff Figure 2 Part of a relational representation of an engineering company Give an E-R diagram and entity types that correspond to this relational representation. Your E-R model should include just four entity types, namely, Staff, CompanyProject, Machine and Machine Training