Chapter07: managing data resources

7.1 © 2003 by Prentice Hall

77

MANAGINGMANAGING

DATA DATA

RESOURCESRESOURCES

Chapter


• Why do businesses have trouble finding Why do businesses have trouble finding the information they need in their the information they need in their information systems?information systems?

• How does a database management system How does a database management system help businesses improve the organization help businesses improve the organization of their information?of their information?

Essentials of Management Information SystemsEssentials of Management Information SystemsChapter 7 Managing Data ResourcesChapter 7 Managing Data Resources

OBJECTIVES


• How do the principal types of database How do the principal types of database models affect the way businesses can models affect the way businesses can access and use information?access and use information?

• What are the managerial and What are the managerial and organizational requirements of a data-organizational requirements of a data-base environment?base environment?

• What new tools and technologies can What new tools and technologies can make databases more accessible and make databases more accessible and useful?useful?

OBJECTIVES



• Organizational obstacles to a Organizational obstacles to a database environmentdatabase environment

• Cost/benefit considerationsCost/benefit considerations

MANAGEMENT CHALLENGES



File Organization Terms and Concepts

• Bit:Bit: Smallest unit of data; binary digit (0,1) Smallest unit of data; binary digit (0,1)

• Byte:Byte: Group of bits that represents a single Group of bits that represents a single charactercharacter

• Field:Field: Group of words or a complete Group of words or a complete numbernumber


ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT


• Record:Record: Group of related fieldsGroup of related fields

• File:File: Group of records of same typeGroup of records of same type

• Database:Database: Group of related filesGroup of related files






Data Hierarchy in a Computer System

Figure 7-1



• Entity:Entity: Person, place, thing, event about Person, place, thing, event about which information is maintainedwhich information is maintained

• Attribute:Attribute: Description of a particular entity Description of a particular entity

• Key field:Key field: Identifier field used to retrieve, Identifier field used to retrieve, update, sort a recordupdate, sort a record






Figure 7-2

Entitities and Attributes




• Data redundancyData redundancy

• Program-Data dependenceProgram-Data dependence

• Lack of flexibilityLack of flexibility

• Poor securityPoor security

• Lack of data-sharing and availabilityLack of data-sharing and availability


Problems with the Traditional File Environment


Traditional File Processing

Figure 7-3




THE DATABASE APPROACH TO DATA MANAGEMENT

• Creates and maintains databasesCreates and maintains databases

• Eliminates requirement for data definition Eliminates requirement for data definition statementsstatements

• Acts as interface between application Acts as interface between application programs and physical data filesprograms and physical data files

• Separates logical and design views of dataSeparates logical and design views of data


Database Management System (DBMS)


The Contemporary Database Environment

Figure 7-4




Components of DBMS

• Data definition language: Data definition language: Specifies Specifies content and structure of database and content and structure of database and defines each data elementdefines each data element

• Data manipulation language:Data manipulation language:Manipulates data in a databaseManipulates data in a database

• Data dictionary:Data dictionary: Stores definitions of Stores definitions of data elements, and data characteristicsdata elements, and data characteristics





Sample Data Dictionary Report


Figure 7-5


Types of Databases

• Relational DBMSRelational DBMS

• Hierarchical and Network DBMSHierarchical and Network DBMS

• Object-Oriented DatabasesObject-Oriented Databases




Relational DBMS


• Represents data as two-dimensional tables Represents data as two-dimensional tables called relationscalled relations

• Relates data across tables based on common Relates data across tables based on common data elementdata element

• Examples: DB2, Oracle, MS SQL ServerExamples: DB2, Oracle, MS SQL Server


7.18 © 2003 by Prentice HallFigure 7-6


Relational Data Model



Three Basic Operations in a Relational Database


• Select:Select: Creates subset of rows that meet Creates subset of rows that meet specific criteriaspecific criteria

• Join:Join: Combines relational tables to provide Combines relational tables to provide users with informationusers with information

• Project:Project: Enables users to create new tables Enables users to create new tables containing only relevant informationcontaining only relevant information





Three Basic Operations in a Relational Database


Hierarchical and Network DBMS

Hierarchical DBMSHierarchical DBMS

• Organizes data in a tree-like structureOrganizes data in a tree-like structure

• Supports one-to-many parent-child Supports one-to-many parent-child relationshipsrelationships

• Prevalent in large legacy systemsPrevalent in large legacy systems




Hierarchical DBMS

Figure 7-8





Network DBMSNetwork DBMS

• Depicts data logically as many-to-many Depicts data logically as many-to-many relationshipsrelationships




Figure 7-9


Network DBMS



DisadvantagesDisadvantages

• OutdatedOutdated

• Less flexible compared to RDBMSLess flexible compared to RDBMS

• Lack support for ad-hoc and English Lack support for ad-hoc and English language-like querieslanguage-like queries





• Object-oriented DBMS:Object-oriented DBMS: Stores data and Stores data and procedures as objects that can be procedures as objects that can be retrieved and shared automatically retrieved and shared automatically

• Object-relational DBMS:Object-relational DBMS: Provides Provides capabilities of both object-oriented and capabilities of both object-oriented and relational DBMSrelational DBMS


Object-Oriented databases



• Conceptual design:Conceptual design: Abstract model of Abstract model of database from a business perspectivedatabase from a business perspective

• Physical design:Physical design: Detailed description of Detailed description of business information needsbusiness information needs

CREATING A DATABASE ENVIRONMENT


Designing Databases


• Entity-relationship diagram:Entity-relationship diagram: Methodology Methodology for documenting databases illustrating for documenting databases illustrating relationships between database entitiesrelationships between database entities

• Normalization:Normalization: Process of creating small Process of creating small stable data structures from complex groups stable data structures from complex groups of dataof data



Designing Databases


An Entity-Relationship Diagram

Figure 7-10






An Unnormalized Relation of ORDER

Figure 7-11




An Normalized Relation of ORDER

Figure 7-12


Centralized databaseCentralized database

• Used by single central processor or multiple Used by single central processor or multiple processors in client/server networkprocessors in client/server network

Distributing Databases




Distributed databaseDistributed database

• Stored in more than one physical locationStored in more than one physical location

• Partitioned database Partitioned database

• Duplicated databaseDuplicated database

Distributing Databases




Distributed Databases

Figure 7-13




Management Requirements for Database Systems

Key elements in a database environment:Key elements in a database environment:

• Data AdministrationData Administration

• Data Planning and Modeling MethodologyData Planning and Modeling Methodology

• Database Technology and ManagementDatabase Technology and Management

• UsersUsers






Management Requirements for Database Systems


Multidimensional Data Analysis

On-line analytical processing (OLAP)On-line analytical processing (OLAP)

• Multidimensional data analysisMultidimensional data analysis

• Supports manipulation and analysis of Supports manipulation and analysis of large volumes of data from multiple large volumes of data from multiple dimensions/perspectivesdimensions/perspectives


DATABASE TRENDS


Multidimensional Data Model

Figure 7-15


DATABASE TRENDS


Data warehouseData warehouse

• Supports reporting and query toolsSupports reporting and query tools

• Stores current and historical data Stores current and historical data

• Consolidates data for management Consolidates data for management analysis and decision makinganalysis and decision making


Data Warehousing and Datamining

DATABASE TRENDS


Components of a Data Warehouse


DATABASE TRENDS

Figure 7-16


Data martData mart

• Subset of data warehouse Subset of data warehouse

• Contains summarized or highly focused Contains summarized or highly focused portion of data for a specified function or portion of data for a specified function or group of usersgroup of users



DATABASE TRENDS


DataminingDatamining

• Tools for analyzing large pools of data Tools for analyzing large pools of data

• Find hidden patterns and infer rules to Find hidden patterns and infer rules to predict trendspredict trends



DATABASE TRENDS


• Improved and easy accessibility to Improved and easy accessibility to informationinformation

• Ability to model and remodel the dataAbility to model and remodel the data


Benefits of Data Warehouses

DATABASE TRENDS



Databases and the Web

The Web and Hypermedia databaseThe Web and Hypermedia database

• Organizes data as network of nodesOrganizes data as network of nodes

• Links nodes in pattern specified by userLinks nodes in pattern specified by user

• Supports text, graphic, sound, video and Supports text, graphic, sound, video and executable programsexecutable programs

DATABASE TRENDS


A Hypermedia Database

Figure 7-17


DATABASE TRENDS


Database serverDatabase server

• Computer in a client/server environment Computer in a client/server environment runs a DBMS to process SQL statements runs a DBMS to process SQL statements and perform database management tasksand perform database management tasks

Application serverApplication server

• Software handling all application Software handling all application operationsoperations


Databases and the Web

DATABASE TRENDS


Linking Internal Databases to the Web

Figure 7-18


DATABASE TRENDS


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MANAGINGMANAGING

DATA DATA

RESOURCESRESOURCES

Chapter

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Chapter07: managing data resources