Difference between a composite key and attribute, Database Management System

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Question:

(a) Discuss the difference between a composite key and a composite attribute. How would each be indicated in an E-R diagram? Support your answer with appropriate example.

(b) Use the following business rules to produce the E-R diagram. Identify at least two attributes for each of the identified entity. You should clearly show all the minimum and cardinality constraint on each side of the relationship.

(i) A department employs many employees, but each employee is employed by one department.

(ii) Some employees, known as "rovers," are not assigned to any department.

(iii) A division operates many departments, but each department is operated by one division.

(iv) An employee may be assigned to many projects and a project may have many employees assigned to it.

(v) A project must have at least one employee assigned to it.

(vi) One of the employees manages each department.

(vii) One of the employees runs each division.

(c) Map the ERD produced into its equivalent Relational Schema.


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