chapter 2 in-class exercises

chapter 2 in-class exercises - COP 4710: Database Systems...

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COP 4710: Database Systems (Chapter 2) Page 1 © Mark Llewellyn COP 4710: Database Systems Fall 2007 Chapter 2 – In Class Exercises School of Electrical Engineering and Computer Science University of Central Florida Instructor : Dr. Mark Llewellyn markl@cs.ucf.edu HEC 236, 823-2790 http://www.cs.ucf.edu/courses/cop4710/fall2007
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COP 4710: Database Systems (Chapter 2) Page 2 © Mark Llewellyn The entity type STUDENT has the following attributes: Student_Name, Address, Phone, Age, Activity, and No_of_years. Activity represents some campus-based student activity, and No_of_years represents the number of years the student has engaged in this activity. A given student may engage in more than one activity. Scenario #1
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COP 4710: Database Systems (Chapter 2) Page 3 © Mark Llewellyn ERD For Scenario #1
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COP 4710: Database Systems (Chapter 2) Page 4 © Mark Llewellyn New Style ERD For Scenario #1 Derived attribute Simple attributes Key attribute Multi-valued attribute Composite attribute
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COP 4710: Database Systems (Chapter 2) Page 5 © Mark Llewellyn A company has a number of employees. The attributes of EMPLOYEE include Emp_ID (identifier), Name, Address, and Birthdate. The company also has several projects. Attributes of PROJECT include Proj_ID (identifier), Proj_Name, and Start_Date. Each employee may be assigned to one or more projects, or may not be assigned to any project. A project must have at least one employee assigned to it, and may have any number of employees assigner to it. An employee’s billing rate may vary by project, and the company wishes to record the applicable billing rate (Billing_Rate) for each employee when assigned to a particular project. Scenario #2
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COP 4710: Database Systems (Chapter 2) Page 6 © Mark Llewellyn ERD For Scenario #2
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COP 4710: Database Systems (Chapter 2) Page 7 © Mark Llewellyn New Style ERD For Scenario #2 Attribute of the relationship Optional participation.
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chapter 2 in-class exercises - COP 4710: Database Systems...

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