Systems analysis and development CIS210 ch 10

Objectives • Upon completion of part II you will be able to: – Understand and be able to explain the concepts related to key database design terminology – Understand and be able to trans

CIS 210

Systems Analysis and Development

Week 6 Part II

Designing Databases

Objectives

• Upon completion of part II you will be able to:

– Understand and be able to explain the concepts related to key database design terminology

– Understand and be able to transform E-R diagrams into an equivalent set of well-structured and normalized relationships – Understand and be able to merge normalized relations from several user views into a consolidated set of well-structured relations

– Understand and be able to explain the concepts related to

storage formats in database tables

– Understand and be able to translate well-structured relations into efficient database tables

– Understand and be able to explain the concepts related to

different methods of storing data in computer files

• Database Design Guidelines

– Database files

– Logical design

– Physical design

• Design Purposes

– Table structure

– Logical design

– Physical design

– Translate relational database model – Choose storage technologies

Database Design

• Logical Database Design

– Four key steps

• Develop model

• Combine requirements

• Translate conceptual model

• Compare logical model with E-R model

• Physical Database Design

– Use results of logical design

– Attributes

– Descriptions of data

– Expectations

– Descriptions of technologies

• Deliverables

– Normalized relations

– Specifications for computer files

Relational Database Model

• Overview

– Data in the form of tables (relations)

– Named columns

– Unnamed rows

• Properties of Relations

– Simple entries in cells

– Column entries from the same set of values – Unique rows

– Interchanged sequence of columns

– Interchanged sequence of rows

• Well-Structured Relations

– Minimum redundancy

– Modification without inconsistency

• Defining Normalization

– Converting complete structures into simple stable data structures

– Based on well-accepted principles and rules

• Functional Dependence and Primary Keys

• Second Normal Form (2NF)

• Third Normal Form (3NF)

– Foreign key

– Referential integrity

Transforming Diagrams Into Relations

• Represent Entities

– Each entity type becomes a relation

– Identifier becomes primary key

– Other attributes become nonprimary keys

• Represent Relationship

– Each relationship must be represented

• Normalize the Relations

• Merge the Relations

Physical File and Database Design

• Designing Fields

– Choosing data types

• Minimize storage space

• Represent all possible values

• Improve data integrity

• Support data manipulations

– Controlling data integrity

• Default value

• Range control

• Referential integrity

• Null value control

Physical File and Database Design

• Designing Physical Tables

– Overview

• Physical table

• Denormalization

– Arranging table rows

• Sequential file organization

• Indexed file organization

• Hashed file organization

– Designing controls for files

• File restoration techniques

• Logical Database Design

• Normalization

• Transforming Diagrams

• Physical File and Database Design