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Chapter 1:

The Database Environment

Modern Database Management7th

Edition

MELJUN CORTES

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Chapter 1 2

Definitions

Data: stored representations of meaningful objects and

events

Structured: numbers, text, dates

Unstructured: images, video, documents

Information: data processed to increase knowledge in

the person using the data

Metadata: data that describes the properties and context

of user data

Database: organized collection of logically related data

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Chapter 1 3

Figure 1-1a Data in context

Context helps users understand data

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Chapter 1 4

Graphical displays turn data into usefulinformation that managers can use for

decision making and interpretation

Figure 1-1b Summarized data

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Chapter 1 5

Descriptions of the properties or characteristics of thedata, including data types, field sizes, allowable

values, and data context

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Chapter 1 6

Disadvantages of File Processing

Program-Data Dependence All programs maintain metadata for each file they use

File descriptions are stored within each application program thataccesses a given file

Duplication of Data Different systems/programs have separate copies of the same data

Limited Data Sharing No centralized control of data

Lengthy Development Times

Programmers must design their own file formats Excessive Program Maintenance

80% of information systems budget

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Chapter 1 7

Figure 1-3 Old file processing systems at Pine Valley

Furniture Company

Duplicate Data

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Chapter 1 8

Problems with Data Redundancy

Waste of space to have duplicate data

Causes more maintenance headaches

The biggest problem:

Data changes in one file could cause

inconsistencies

Compromises in data integrity

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Chapter 1 9

SOLUTION:

The DATABASE Approach

Central repository of shared data

Data is managed by a controlling agent

Stored in a standardized, convenientform

Requires a Database Management System (DBMS)

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Chapter 1 10

Database Management

System

DBMS manages data resources like an operating system manages hardware resources

A software system that is used to create, maintain, and provide

controlled access to user databases

Order FilingSystem

InvoicingSystem

Payroll

System

DBMSCentral database

Contains employee,order, inventory,

pricing, and

customer data

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Chapter 1 11

Advantages of the Database Approach

Program-data independence- The separation of data descriptions (metadata) fromthe application programs that use the data

Planned data redundancy

Improved data consistency

Improved data sharing

Increased application development productivity

Enforcement of standards

Improved data quality

Constraint rule that cannot be violated by databaseusers

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Chapter 1 12

Advantages of the Database Approach

Improved data accessibility and responsiveness Reduced program maintenance

Improved decision support

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Chapter 1 13

Costs and Risks of the Database

Approach

New, specialized personnel

Installation and management cost andcomplexity

Conversion costs

Legacy system refers to older applications in anorganization

Need for explicit backup and recovery Organizational conflict

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Chapter 1 14

Figure 1-5 Components of the Database Environment

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Chapter 1 15

Components of the

Database Environment

CASE Toolscomputer-aided software engineering Automated tools used to design databases and application

programs

Repositorycentralized storehouse of metadata

Database Management System (DBMS)software for managing

the database Databasestorehouse of the data

Application Programssoftware using the data

User Interfacetext and graphical displays to users

Data/Database Administratorspersonnel responsible for

maintaining the database System Developerspersonnel responsible for designing

databases and software

End Userspeople who use the applications and databases

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Chapter 1 16

The Range of Database Applications

Personal databases

Workgroup databases

Departmental/divisional databases

Enterprise database

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Chapter 1 17

Figure 1-6

Typical data

from apersonal

database

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Chapter 1 18

Figure 1-7 Workgroup database with wireless

local area network

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Chapter 1 19

Figure 1-8 An enterprise data warehouse

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Chapter 1 20

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Chapter 1 21

Extranet use of internet protocols to establish

limited access to company data and information

by the companys customers and suppliers.

Intranet use of internet protocols to establish

access to company data and information that is

limited to the organization.