Chapter 3(7) IS 230 - King Saud University College of...

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07/01/1438 >#< 1 Introduction to Database Systems Fall 2016 Dr. Ahmed Emam [email protected] [email protected] King Saud University College of Computer and Information Sciences Department of Information Systems DATA MODELING USING THE ENTITY- RELATIONSHIP (ER) MODEL
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07/01/1438 >#< 2 Chapter 7 Outline Using High-Level Conceptual Data Models for Database Design A Sample Database Application Entity Types, Entity Sets, Attributes, and Keys Relationship Types, Relationship Sets, Roles, and Structural Constraints Weak Entity Types Refining the ER Design for the COMPANY Database ER Diagrams, Naming Conventions, and Design Issues Example of Other Notation: UML Class Diagrams Relationship Types of Degree Higher than Two Data Modeling Using the Entity-Relationship (ER) Model Entity-Relationship (ER) model Popular high-level conceptual data model ER diagrams Diagrammatic notation associated with the ER model Unified Modeling Language (UML)
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07/01/1438 >#< 3 Using High-Level Conceptual Data Models for Database Design Requirements collection and analysis Database designers interview prospective database users to understand and document data requirements Result: data requirements Functional requirements of the application Using High-Level Conceptual Data Models Cont. Conceptual schema Conceptual design Description of data requirements Includes detailed descriptions of the entity types, relationships, and constraints Transformed from high-level data model into implementation data model
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07/01/1438 >#< 4 Using High-Level Conceptual Data Models Cont. Logical design or data model mapping Result is a database schema in implementation data model of DBMS Physical design phase Internal storage structures, file organizations, indexes, access paths, and physical design parameters for the database files specified A Sample Database Application COMPANY Employees, departments, and projects Company is organized into departments Department controls a number of projects Employee: store each employee s name, Social Security number, address, salary, sex (gender), and birth date Keep track of the dependents of each employee
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07/01/1438 >#< 5 Entities and Attributes Entity Thing in real world with independent existence Attributes Particular properties that describe entity Types of attributes: Composite versus simple (atomic) attributes Single-valued versus multivalued attributes Stored versus derived attributes NULL values Complex attributes
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07/01/1438 >#< 6 Entity Types, Entity Sets, Attributes, and Keys ER model describes data as: 1. Entities 2. Relationships 3. Attributes Entity Sets A database can be modeled as: a collection of entities, relationship among entities.
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