1. OS App. 1 App. 2 App. 3 OS App. 1 App. 2 App. 3 DBMSDBMS OS App. 1 App. 2 App. 3 O-O D B M S Data Design Files & Databases

2. Traditional File Systems Advantages: –Simple Data Design - to support single or small group applications –Fast Data Access –Inexpensive Disadvantages: –Lack of data relation –Redundancy –Lack of standards –Low application development productivity DBMS: Integration, sharing of data Increased data accessibility Minimum redundancy

3. Easier application development and maintenance Improved Data security Logical / Physical data independence Disadvantages: Complex data design Slow access Expensive

4. Data Modelling: Modelling Object (Entity) classes, Attributes and relationships Data Modelling/ Object Structure analysis and design Logical Data Design Physical Database design Entity, Attributes, Instances: Customer Cust Name City Zip Phone # Cust # Unique Identifier: Cust# ( Primary Key)

5. Relationships between Object Classes/ Entities: How are instance relates to another (Business rules and Policies) Customer Sales Transactions initiates 0 to many Is initiated by 1 and only 1 CustomerSales Transaction Cardinality Min Max Min = 1Existence Dependency

6. E/ R Model: CustomerSales Transaction Min Max A A A A A A B B B B B B 1,35 Each Instance of class A is associated with one and only one instance of class B

8. Recursive Relation Course Course ID Subject Course Course Title Course Credit Is a prerequisite for Has as a pre-requisite

9. Generalization/ Specialization Person TeacherStudents Inheritance No Cardinality ( 1 to 1) Person TeacherStudents Mutually Exclusive Major GPA Dept Salary SS# Name Address

10. Composition Relationship (HAS - A) An object instance is composed of one or more instances of another object class Sales Transaction ST Line

11. COURSE CourseID Course Title Credit Subject Course # INSTRUCTOR InstrID Last Name First Name SCHEDULED CLASS SchedClassID Day of Week Start Time End Time CourseID InstrID RoomID ROOM RoomID Capacity Bldg Room# N-ary Relationships - Use an Association

12. Some Guidelines Identifying Classes –each class has data it must remember –each class has at least one attribute –class has several attributes –all instances have same attribute ( & methods) Assigning Attributes to Object classes –each attribute appears only once –assign attribute to object class that it most logically describes Identifiers (Pks) for each class –sub-class assumes identifier of super-class

13. Completed Object Relationship Model

14. Object Relationship Model with Attributes and Identifiers

15. CASE

16. Sales Transaction Order # Order Date Xact. Type Sub Total Sales Tax Total Cash Sale Amt Rcvd Pmt Type Credit Order Amt Charged App. Code Order PickUp Pickup #

17. flight

18. Flight Flt # Dep Time Dep City Arr. Time Arr City Capacity Reservation Ticket # Dep Date Ticket Class Ticket Condition. Fare Customer Cust Name Cust Address Cust Number Q2:

21. Deduction Ded-Type Ded Amt Department Dept. Name Time Card Pay Period Ending TC-Line Date Time-In Time-Out TS-Line Hrs-Worked Gross Pay Time Sheet Pay Period Ending Employee SSN Emp Name Tax Status Exempts Hourly Rate YTO-Gross Last Update Time Card will have TC-Lines for employees on vacation Each TS-Line is related to only one time-card