concepts of database management, fifth edition chapter 1: introduction to database management

Concepts of Database Concepts of Database Management, Fifth Management, Fifth

EditionEdition

Chapter 1: Chapter 1:

Introduction to Introduction to Database ManagementDatabase Management

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Objectives

Why study database management? Introduce Premiere Products, the company

that is used as the basis for many of the examples throughout the text

Introduce basic database terminology

Describe database management systems

Explain the advantages and disadvantages of database processing

Introduce Henry Books, the company that is used in the case that runs throughout the text

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Why manage data?Why manage data?

Changing view of data

Higher costs of lost data

Encouragement of “team problem-solving”

Flexible reporting Integrating it into

decision-making better

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Background Info Background Info DBMS software

$25B/year industry Networked DBMS

growing fastest DB research underpins

communication systems Enterprise applications multimedia Internet scientific applications

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Data Management Tasks Data Management Tasks

designing the file or database structure entering the data updating data by adding, changing,

or deleting sorting the data searching through the data for a record or

group of records obtaining screen or printed output

Common tasks for flat files and databases are:

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Approaches to Data Management include:

Approaches to Data Management include:

Custom Program Approach File Processing System Approach Database Management System

Approach

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Contrasting Database and File System Designs

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Problems associated with file processing systems

Problems associated with file processing systems

Application/Program dependence

Data is separate and isolated

Data reduplication Multiple formats; hard

to share data across applications.

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Database Management Systems

Database Management Systems

OperatingSystem

DatabaseManagement

System

ApplicationPrograms

OperatingSystem

DatabaseManagement

System

ApplicationPrograms

Databases

DataDictionary

DatabaseManagement

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Disadvantages of DBMS ApproachDisadvantages of DBMS Approach

Cost Size Complexity Additional Hardware

Requirements Higher Impact of

Failure Recovery more

difficult

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Major Types of DatabasesMajor Types of Databases

DatabaseServer

DatabaseServer

ExternalDatabases

End UserWorkstation

OperationalDatabases

AnalyticalDatabases

DataWarehouseDatabases

End UserDatabases

DistributedDatabases

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Database Management Systems

Program(s) through which users interact with database

Popular DBMSs include

Access

Oracle

DB2

SQL Server

Premiere Products decides to use Access

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DBMS ClassificationsDBMS Classifications Platform

Stand alone Network Mainframe

Organizational Level `Individual Workgroup Enterprise-wide (ex. SAP use of Oracle)

Data Model Supported Hierarchical Network Relational Object-Oriented

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Database Models Database Models

Hierarchical Network Relational Object-oriented

details follow

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Logical Data ElementsLogical Data ElementsPersonnelDatabase

EmployeeRecord 2

EmployeeRecord 1

EmployeeRecord 3

EmployeeRecord 4

Name SS Salary Name SS Salary Name SS Salary Name SS Salary

Data Data Data Data Data Data Data Data Data Data Data Data

PayrollFile

BenefitsFile

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Database StructuresDatabase Structures

Dept

A

B

C

Empno Dept

1 A

2 B

3 C

Relational Structure

Network StructureHierarchical Structure

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Premiere Products

Distributor of appliances, house wares, and sporting goods

Uses spreadsheet software to maintain important data

Recent growth has made spreadsheet approach problematic

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Figure 1.1: Sample Orders Spreadsheet

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Problems Using Spreadsheet

Redundancy

Duplication of data or the storing of the same data in more than one place

Occurs when the same information is stored in more than one place

Difficulty accessing data

Limited security

Size limitations

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Premiere Products Required Information

Sales Reps

Sales rep number, last name, first name, address, total commission, commission rate

Customers

Customer number, name, address, current balance, credit limit, customer sales rep

Parts Inventory

Part number, description, number units on hand, item class, warehouse number, unit price

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Figure 1.2: Premiere Products Sample Order

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Premiere Products Customer Order Order

Order number, order date, customer number

Order line

Order number, part number, number units ordered, unit price

Overall order total

Not stored since it can be calculated

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Database Background Database

Structure that can store information about

Multiple types of entities

Attributes of those entities

Relationships among entities

Entity

Person, place, thing, or event

Premiere Products has sales reps, customers, orders, and parts

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Database Background (con’t)

Attribute

Property of an entity

Customer has name, street, city, et cetera

May also be called a field or column

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Figure 1.3: Entities and Attributes

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Database Background (con’t.) Relationship

Association between entities

One-to-many relationship - rep is related to many customers

Customer is related to a single rep

Data file

File used to store data

Computer counterpart to ordinary paper file

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Figure 1.4: One-to-Many Relationship

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Figure 1.5: Rep and Customer Tables

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Figure 1.5: Orders and OrderLine Tables (con’t.)

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Figure 1.5: Part Table (con’t.)

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Figure 1.6: Alternative Orders Table

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Entity-relationship Diagram

Visual way to represent a database

Rectangles represent entities

Lines represent relationships between connected entities

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Figure 1.7: E-R Diagram

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Figure 1.8 and 1.9: Using DBMSs in Different Ways

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Building a Database

Database design determines the structure of a database

Design entered into DBMS during construction Tables – stores data

Forms – screen objects used to maintain, view, and print from a database

Reports – provides formatted output

Switchboards – a set of special forms used to provide controlled access to the data, forms, report and other objects in a database

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Figures 1.10 and 1.11: Part and Order Forms

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Figure 1.12: Parts Report

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Figure 1.13: Main Switchboard

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Figure 1.14: Main Data Switchboard

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Figure 1.15: Advantages of Database Processing

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Figure 1.16: Disadvantages of Database Processing

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Introduction to Henry Books Database Case

Book store chain operated by Ray Henry

Henry decided to use database to gather and store information on:

Branches

Publishers

Authors

Books

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Figure 1.17: Sample Branch Data

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Figure 1.17: Sample Publisher Data (con’t.)

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Figure 1.18: Sample Author Data

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Figure 1.19: Sample Book Data

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Figure 1.20: Wrote Table Relates Authors to Books

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Figure 1.20: Inventory Table Relates Branches to Books (con’t.)

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Summary Nondatabase approaches to management have

problems with replication, redundancy, sharing, limited security, and size limitations

Entity - a person, place, object, event, or idea for which you want to store and process data

Attribute, field, or column - a characteristic or property of an entity

Relationship - an association between entities

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Summary One-to-many relationship - exists when

Each occurrence of the first entity is related to many occurrences of the second entity

Each occurrence of the second entity is related to only one occurrence of the first entity

Database is a structure that can store information about multiple types of entities

An entity-relationship (E-R) diagram represents a database pictorially

Database management system (DBMS) - a program, or a collection of programs, through which users interact with a database

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Summary Advantages to database processing:

Getting more information from the same amount of data

Sharing data Balancing conflicting requirements Controlling redundancy Facilitating consistency Improving integrity Expanding security Increasing productivity Providing data independence

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Summary Disadvantages of database processing:

Larger file size

Increased complexity

Greater impact of failure

More difficult recovery