Data Conversion - Information Systems Reengineering, Integration and Normalization - page 160

In the example, we can normalize the class Employee by decomposing into two
classes: Employees and Department as follows:

Class Employee Class Department
attr Employee#: integer attrDept_name: string
attr Employee_name: string attr Dept_budget: integer
attr Salary: integer attr location: set(string)
associationattrhired_by ref Department associationattr hire ref

end set(Employee

end

After the normalization, the update anormalies are eliminated since the decomposed
two class objects can be updated independently.

4.7.1 Case Study of Data Conversion from Relational to

Object-Oriented

To illustrate the application of the above methodology, we can use a modified uni-
versity enrollment system as an example.
Relation Course

Course Course_title Location

CS101 Intro to Computer Science Lecture Theatre 1

IS201 System Analysis Lecture Theatre 2

IS301 Decision Support System Room P7818

Relation Prerequisite

*Course# Prerequisite Prereq_title

IS301 IS201 System Analysis

Relation Instructor

SS# Inst_name Inst_addr

415223641 A.B.Adams White Plains

613557642 J.S. Fink Brooklyn

452113641 A.M.Jones Long Island