Lecture_2_-_Relational_Database_System

Lecture_2_-_Relational_Database_System - CSCI-507 Database...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
1 1 c Database Systems, 9th Edition CSCI-507 Database Theory Lecture 2 – Data Modeling 2 Objectives In this chapter, you will learn: About data modeling and why data models are important About the basic data-modeling building blocks What business rules are and how they influence database design How the major data models evolved How data models can be classified by level of abstraction That the relational database model offers a logical view of data About the relational model’s basic component: relations That relations are logical constructs composed of rows (tuples) and columns (attributes) That relations are implemented as tables in a relational DBMS
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 3 Objectives (cont’d.) About relational database operators, the data dictionary, and the system catalog How data redundancy is handled in the relational database model Why indexing is important 4 Part 1 About Data Modeling
Background image of page 2
3 5 Introduction • Designers, programmers, and end users see data in different ways • Different views of same data lead to designs that do not reflect organization’s operation • Data modeling reduces complexities of database design • Various degrees of data abstraction help reconcile varying views of same data 6 Data Modeling and Data Models • Data models – Relatively simple representations of complex real-world data structures • Often graphical • Model: an abstraction of a real-world object or event – Useful in understanding complexities of the real-world environment • Data modeling is iterative and progressive
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 7 The Importance of Data Models • Facilitate interaction among the designer, the applications programmer, and the end user • End users have different views and needs for data • Data model organizes data for various users • Data model is an abstraction – Cannot draw required data out of the data model 8 Data Model Basic Building Blocks • Entity: anything about which data are to be collected and stored • Attribute: a characteristic of an entity • Relationship: describes an association among entities – One-to-many (1:M) relationship – Many-to-many (M:N or M:M) relationship – One-to-one (1:1) relationship • Constraint: a restriction placed on the data
Background image of page 4
5 9 Business Rules • Descriptions of policies, procedures, or principles within a specific organization – Apply to any organization that stores and uses data to generate information • Description of operations to create/enforce actions within an organization’s environment – Must be in writing and kept up to date – Must be easy to understand and widely disseminated • Describe characteristics of data as viewed by the company 10 Discovering Business Rules • Sources of business rules: – Company managers – Policy makers – Department managers – Written documentation • Procedures • Standards • Operations manuals – Direct interviews with end users
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 11 Discovering Business Rules (cont’d.) • Standardize company’s view of data
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 51

Lecture_2_-_Relational_Database_System - CSCI-507 Database...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online