1. Chapter Two ( Data Model) Objectives Introduction to Data Models What are the Data Models Why they are important Learn how to design a DBMS

2. 2 Data Model: Model: Importance of data model: Relatively simple representations, usually graphical, of complex real-world data structures

3. 3 Data Model: Facilitate interaction among the designer(s), the applications programmer(s), and the end user(s)

4. Database Models: Hierarchical Model Network Model Relational Model Entity Relationship (ER) Model

5. 5 Entity-Relationship Model (ER-Model) Purpose of ER Model is to allow the description of an enterprise to be written without the attention to the efficiency or the physical design.

6. 6 Entity-Relationship Model (ER-Model) A set of basic objects called Entity, and a set of Relationships among objects (Entities)

7. 7 Entity and Entity Set: Entity: An object that exists and is distinguishable from other objects Car ? VW? Entity Set: A set of entities of the same type Entity set needs not be disjoint (Faculty vs Student)

8. 8 Entity and Entity Set: (Continued) An entity is represented by a set of attributes Student(Name, Id, Gpa) Each attribute has a set of permitted values called Domain (value set) Id: positive integer

9. 9 Relationship and Relationship Sets: Relationship is an association among two or more entities Faculty and Course Relationship Set: is a set of similar relationships

10. 10 Business Rules: Brief, precise, and unambiguous descriptions of a policies, procedures, or principles within a specific organization Apply to any organization that stores and uses data to generate information Description of operations that help to create and enforce actions within that organization’s environment

11. 11 Sources of Business Rules: Company managers Policy makers Department managers Written documentation Procedures Standards Operations manuals Direct interviews with the end users

12. 12 Translating Business Rules into Data Model: Standardize company’s view of data Constitute a communications tool between users and designers Allow designer to understand the nature, role, and scope of data Allow designer to understand business processes Allow designer to develop appropriate relationship participation rules and constraints Promote creation of an accurate data model

13. 13 Steps in designing a database using ER Model 1. Identify a. Entity sets b. Relationship sets 2. Identify semantic Info. In the relationship sets 3. Define the value sets of attributes 4. Organize data into Entity/Relationships

14. 14 Database Lifecycle 1. Analysis:  Study and analyze business requirements  Interview managers and users for the information requirements  Develop a system specification

15. 15 Database Lifecycle 2. Design (Data Models)  Entity relational model (ER)  Unify modeling language (UML)  Check the design 3. Build the Databases/Document/Test  Create tables and views, and programs  Produce manuals

16. 16 Database Life Cycle 4. Product delivery  Load the software  Monitor the performance

17. 17 Practice (Analysis): Discuss a database system for an organization: