MELJUN CORTES Database Environment
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Transcript of MELJUN CORTES Database Environment
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1
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.