Database System: Chapter 5 - Data Modeling Using the (Enhanced) Entity-Relationship (E-ER) Model provides about Example Database Application (COMPANY), ER Model Concepts, ER Diagrams - Notation, ER Diagram for COMPANY Schema, Enhanced Entity Diagram. | Chapter 5 Data Modeling Using the (Enhanced) Entity-Relationship (E-ER) Model Copyright © 2004 Pearson Education, Inc. 5/14/2020 4:10:15 AM Outline Example Database Application (COMPANY) ER Model Concepts Entities and Attributes Entity Types, Value Sets, and Key Attributes Relationships and Relationship Types Weak Entity Types Roles and Attributes in Relationship Types ER Diagrams - Notation ER Diagram for COMPANY Schema Enhanced Entity Diagram Slide 5 - Example COMPANY Database Requirements of the Company (oversimplified for illustrative purposes) The company is organized into DEPARTMENTs. Each department has a name, number and an employee who manages the department. We keep track of the start date of the department manager. Each department controls a number of PROJECTs. Each project has a name, number and is located at a single location. Slide 5 - Example COMPANY Database (Cont.) We store each EMPLOYEE’s social security number, address, salary, sex, and birthdate. Each | Chapter 5 Data Modeling Using the (Enhanced) Entity-Relationship (E-ER) Model Copyright © 2004 Pearson Education, Inc. 5/14/2020 5:23:41 AM Outline Example Database Application (COMPANY) ER Model Concepts Entities and Attributes Entity Types, Value Sets, and Key Attributes Relationships and Relationship Types Weak Entity Types Roles and Attributes in Relationship Types ER Diagrams - Notation ER Diagram for COMPANY Schema Enhanced Entity Diagram Slide 5 - Example COMPANY Database Requirements of the Company (oversimplified for illustrative purposes) The company is organized into DEPARTMENTs. Each department has a name, number and an employee who manages the department. We keep track of the start date of the department manager. Each department controls a number of PROJECTs. Each project has a name, number and is located at a single location. Slide 5 - Example COMPANY Database (Cont.) We store each EMPLOYEE’s social security number, address, salary, sex, and birthdate. Each employee works for one department but may work on several projects. We keep track of the number of hours per week that an employee currently works on each project. We also keep track of the direct supervisor of each employee. Each employee may have a number of DEPENDENTs. For each dependent, we keep track of their name, sex, birthdate, and relationship to employee. Slide 5 - ER Model Concepts Entities and Attributes Entities are specific objects or things in the mini-world that are represented in the database. For example the EMPLOYEE John Smith, the Research DEPARTMENT, the ProductX PROJECT Attributes are properties used to describe an entity. For example an EMPLOYEE entity may have a Name, SSN, Address, Sex, BirthDate A specific entity will have a value for each of its attributes. For example a specific employee entity may have Name='John Smith', SSN='123456789', Address ='731, Fondren, Houston, TX', Sex='M', BirthDate='09-JAN-55‘ Each attribute has a value set (or data type) .
