tailieunhanh - Lecture Systems analysis and design methods (7/e): Chapter 8 – Whitten, Bentley

In this chapter you will learn how to use a popular data-modeling tool, entity relationship diagrams, to document the data that must be captured and stored by a system, independently of showing how that data is or will be used—that is, independently of specific inputs, outputs, and processing. You will also learn about a data analysis technique called normalization that is used to ensure that a data model is a “good” data model. | Chapter 8 Data Modeling and Analysis Objectives Define data modeling and explain its benefits. Recognize and understand the basic concepts and constructs of a data model. Read and interpret an entity relationship data model. Explain when data models are constructed during a project and where the models are stored. Discover entities and relationships. Construct an entity-relationship context diagram. Discover or invent keys for entities and construct a key-based diagram. Construct a fully attributed entity relationship diagram and describe data structures and attributes to the repository. Normalize a logical data model to remove impurities that can make a database unstable, inflexible, and nonscalable. Describe a useful tool for mapping data requirements to business operating locations. 8- 8- Data Modeling Data modeling – a technique for organizing and documenting a system’s data. Sometimes called database modeling. Entity relationship diagram (ERD) – a data model utilizing . | Chapter 8 Data Modeling and Analysis Objectives Define data modeling and explain its benefits. Recognize and understand the basic concepts and constructs of a data model. Read and interpret an entity relationship data model. Explain when data models are constructed during a project and where the models are stored. Discover entities and relationships. Construct an entity-relationship context diagram. Discover or invent keys for entities and construct a key-based diagram. Construct a fully attributed entity relationship diagram and describe data structures and attributes to the repository. Normalize a logical data model to remove impurities that can make a database unstable, inflexible, and nonscalable. Describe a useful tool for mapping data requirements to business operating locations. 8- 8- Data Modeling Data modeling – a technique for organizing and documenting a system’s data. Sometimes called database modeling. Entity relationship diagram (ERD) – a data model utilizing several notations to depict data in terms of the entities and relationships described by that data. 8- Sample Entity Relationship Diagram (ERD) 8- Persons: agency, contractor, customer, department, division, employee, instructor, student, supplier. Places: sales region, building, room, branch office, campus. Objects: book, machine, part, product, raw material, software license, software package, tool, vehicle model, vehicle. Events: application, award, cancellation, class, flight, invoice, order, registration, renewal, requisition, reservation, sale, trip. Concepts: account, block of time, bond, course, fund, qualification, stock. Data Modeling Concepts: Entity Entity – a class of persons, places, objects, events, or concepts about which we need to capture and store data. Named by a singular noun 8- Data Modeling Concepts: Entity Entity instance – a single occurrence of an entity. Student ID Last Name First Name 2144 Arnold Betty 3122 Taylor John 3843 Simmons Lisa 9844 Macy