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 [email protected] 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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(Chapter 2) Page 7 © Mark Llewellyn New Style ERD For Scenario #2 Attribute of the relationship Optional participation. Not every
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This note was uploaded on 02/22/2009 for the course COP 4710 taught by Professor Dr. mark llewellyn during the Fall '07 term at University of Central Florida.

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

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