Stimulate 2005
Instructor: Luz Quiroga
Exercise from C&B: 11.10
Entity Relationship Class Exercise Solution
11.10
Create an ER diagram for each of the following descriptions:
(a)
Each company operates four departments, and each department belongs to one company.
Operates
Company
(b)
Department
1..1
4
Each department in part (a) employs one or more employees, and each employee works
for one department.
Employs
Department
Employee
1..1
(c)
1..*
Each of the employees in part (b) may or may not have one or more dependants, and each
dependant belongs to one employee.
Has
Employee
(d)
1..1
0..*
Dependent
Each employee in part (c) may or may not have an employment history.
Provides
Employee
1..1
Employment
0..*
History
(e)
Represent all the ER diagrams described in (a), (b), (c), and (d) as a single ER diagram.
Operates
Company
Department
1..1
4
1..1
Employs
1..*
Provides
Employment
History
Employee
0..*
1..1
1..1
Has
0..*
Dependent