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ManagementManagement
Information Systems,Information Systems,
10/e10/e
Raymond McLeod and George SchellRaymond McLeod and George Schell

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Chapter 6Chapter 6
Database Management SystemsDatabase Management Systems

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Learning ObjectivesLearning Objectives
► Understand the hierarchy of data.Understand the hierarchy of data.
► Understand database structures and how theyUnderstand database structures and how they
work.work.
► Know how to relate tables together in a database.Know how to relate tables together in a database.
► Recognize the difference between a database andRecognize the difference between a database and
a database management system.a database management system.
► Understand the database concept.Understand the database concept.
► Know two basic methods for determining dataKnow two basic methods for determining data
needs.needs.

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Learning Objectives (Cont’d)Learning Objectives (Cont’d)
► Understand entity-relationship diagrams and classUnderstand entity-relationship diagrams and class
diagrams.diagrams.
► Know the basics of reports and forms.Know the basics of reports and forms.
► Understand the basic difference betweenUnderstand the basic difference between
structured query language and query-by-example.structured query language and query-by-example.
► Know about the important personnel who areKnow about the important personnel who are
associated with databases.associated with databases.
► Know the advantages and costs of databaseKnow the advantages and costs of database
management systems.management systems.

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Data HierarchyData Hierarchy
►Data fieldData field is the smallest unit of data.is the smallest unit of data.
►RecordRecord is a collection of related data fields.is a collection of related data fields.
►FileFile is a collection of related records.is a collection of related records.
►DatabaseDatabase is a collection of related files.is a collection of related files.
 General definitionGeneral definition
 Restrictive definitionRestrictive definition

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DatabaseDatabase
► Table of rows & columns can be represented in aTable of rows & columns can be represented in a
spreadsheet.spreadsheet.
► Relational database structureRelational database structure is conceptuallyis conceptually
similar to a collection of related tables.similar to a collection of related tables.
► Flat fileFlat file is a table that does not have repeatingis a table that does not have repeating
columns; 1columns; 1stst
normal form.normal form.
► NormalizationNormalization is a formal process for eliminatingis a formal process for eliminating
redundant data fields which preserving the abilityredundant data fields which preserving the ability
of the database to add, delete, and modify recordsof the database to add, delete, and modify records
without causing errors.without causing errors.

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Figure 6.1 Spreadsheet as a SimpleFigure 6.1 Spreadsheet as a Simple
DatabaseDatabase

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Database (Cont’d)Database (Cont’d)
► KeyKey in a table is a field (or combination of fields)in a table is a field (or combination of fields)
that contain a value that uniquely identifies eachthat contain a value that uniquely identifies each
record in the table.record in the table.
► Candidate keyCandidate key is a field that uniquely identifiesis a field that uniquely identifies
each table row but is not the chosen key.each table row but is not the chosen key.
► Relating tables is done through sharing a commonRelating tables is done through sharing a common
field & the value of the field determines which rowsfield & the value of the field determines which rows
in the tables are logically joined.in the tables are logically joined.

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Database Management SystemDatabase Management System
►Database management systemDatabase management system
(DBMS)(DBMS) is a software application thatis a software application that
stores the structure of the database, thestores the structure of the database, the
data itself, relationships among data in thedata itself, relationships among data in the
database, and forms & reports pertaining todatabase, and forms & reports pertaining to
the database.the database.
 Self-describing set of related data.Self-describing set of related data.

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Database StructuresDatabase Structures
►HierarchicalHierarchical is formed by data groups,is formed by data groups,
subgroups, and further subgroups; likesubgroups, and further subgroups; like
branches on a tree.branches on a tree.
 Worked well with TPSs.Worked well with TPSs.
 Utilized computer resources efficiently.Utilized computer resources efficiently.
►NetworkNetwork allows retrieval of specificallows retrieval of specific
records; allows a given record to point torecords; allows a given record to point to
any other record in the database.any other record in the database.

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Figure 6.2 Hierarchical StructureFigure 6.2 Hierarchical Structure

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Database Structures (Cont’d)Database Structures (Cont’d)
►RelationalRelational is when the relationshipis when the relationship
between tables are implicit.between tables are implicit.
►Physical relationshipPhysical relationship is when theis when the
database structure (hierarchical, network)database structure (hierarchical, network)
rely on storage addresses.rely on storage addresses.
►Implicit relationshipImplicit relationship is when theis when the
database structure (relational) can bedatabase structure (relational) can be
implied from the data.implied from the data.

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A Relational Database ExampleA Relational Database Example
►A database namedA database named ScheduleSchedule has been createdhas been created
from tables used earlier in the chapter and somefrom tables used earlier in the chapter and some
othersothers
►The database is implemented in MicrosoftThe database is implemented in Microsoft
Access 2002 (also known as Access XP).Access 2002 (also known as Access XP).
►Databases break information into multiple tablesDatabases break information into multiple tables
because if information were stored in a singlebecause if information were stored in a single
table, many data field values would betable, many data field values would be
duplicated.duplicated.

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ScheduleSchedule DatabaseDatabase
► The example is implemented on Microsoft Access DBMS butThe example is implemented on Microsoft Access DBMS but
would be similar on any relational DBMS product.would be similar on any relational DBMS product.
► The COURSE table in Access (Figure 6.4) is a list of data fieldThe COURSE table in Access (Figure 6.4) is a list of data field
values. The table itself had to be defined in Access before valuesvalues. The table itself had to be defined in Access before values
were entered into the data fields.were entered into the data fields.
► Figure 6.5 shows the definition of theFigure 6.5 shows the definition of the CodeCode field.field.
► Figure 6.6 illustrates thatFigure 6.6 illustrates that AbbreviationAbbreviation field values will befield values will be
looked up from a list of values in the DEPARTMENT table.looked up from a list of values in the DEPARTMENT table.
► Table 6.7 shows a single table of course and department fieldsTable 6.7 shows a single table of course and department fields
before they were separated into different tables.before they were separated into different tables.

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Figure 6.4 The COURSE TableFigure 6.4 The COURSE Table

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Figure 6.5 Defining the CODE FieldFigure 6.5 Defining the CODE Field

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Figure 6.6 Look-up ValuesFigure 6.6 Look-up Values

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Table 6.7Table 6.7

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Figure 6.7 Access ViewFigure 6.7 Access View

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Database ConceptDatabase Concept
► Database conceptDatabase concept is the logical integration ofis the logical integration of
records across multiple physical locations.records across multiple physical locations.
► Data independenceData independence is the ability to makeis the ability to make
changes in the data structure without makingchanges in the data structure without making
changes to the application programs that accesschanges to the application programs that access
the data.the data.
► Data dictionaryData dictionary includes the definition of theincludes the definition of the
data stored within the database & controlled by thedata stored within the database & controlled by the
database management system.database management system.

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Creating a DatabaseCreating a Database
►Determine data that needs to be collected &Determine data that needs to be collected &
stored is a key step.stored is a key step.
►Process-oriented approachProcess-oriented approach
 Define the problem.Define the problem.
 Identify necessary decisions.Identify necessary decisions.
 Describe information needs.Describe information needs.
 Determine the necessary processing.Determine the necessary processing.
 Specify data needs.Specify data needs.

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Determine Data Needs (Cont’d)Determine Data Needs (Cont’d)
►Enterprise modeling approachEnterprise modeling approach takes atakes a
broad view of the firm’s data resources; allbroad view of the firm’s data resources; all
areas are considered, & synergy of dataareas are considered, & synergy of data
resources between business areas can beresources between business areas can be
leveraged.leveraged.
 Result:Result: Enterprise data modelEnterprise data model

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Figure 6.8 Enterprise Data ModelFigure 6.8 Enterprise Data Model

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Data Modeling TechniquesData Modeling Techniques
►Entity-relationship diagrams (ERDs)Entity-relationship diagrams (ERDs)
is a graphical representation of data inis a graphical representation of data in
entities and the relationships betweenentities and the relationships between
entities.entities.
►EntityEntity is a conceptual collection of relatedis a conceptual collection of related
data fields.data fields.
►RelationshipRelationship is defined between entities.is defined between entities.
 One-to-one – 1:1One-to-one – 1:1
 One-to-many – 1:MOne-to-many – 1:M
 Many-to-many – M:NMany-to-many – M:N

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Figure 6.11 Entity-relationshipFigure 6.11 Entity-relationship
DiagramDiagram

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Diagramming Techniques (Cont’d)Diagramming Techniques (Cont’d)
►Class DiagramClass Diagram is a graphicalis a graphical
representation of both the data used in anrepresentation of both the data used in an
application and the actions associated withapplication and the actions associated with
the data; object-oriented design modelthe data; object-oriented design model
►ObjectsObjects are the data, actions taken on theare the data, actions taken on the
data, & relationship between objects.data, & relationship between objects.
►Class diagrams consist of the named class,Class diagrams consist of the named class,
fields in the class, & actions (fields in the class, & actions (methodsmethods) that) that
act upon the class.act upon the class.

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Figure 6.13 Class DiagramFigure 6.13 Class Diagram

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Using the DatabaseUsing the Database
►FormsForms show 1 record at a time & can beshow 1 record at a time & can be
used to add, delete, or modify databaseused to add, delete, or modify database
records.records.
 NavigationNavigation
 AccuracyAccuracy
 ConsistencyConsistency
 FilteringFiltering
 subformssubforms

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Figure 6.15 Combined Data EntryFigure 6.15 Combined Data Entry
FormForm

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Using the Database (Cont’d)Using the Database (Cont’d)
►ReportsReports are aggregated data from theare aggregated data from the
database that are formatted in a mannerdatabase that are formatted in a manner
that aids decision making.that aids decision making.
►QueriesQueries is a request for the database tois a request for the database to
display selected records.display selected records.
►Query-by-example (QBE)Query-by-example (QBE) presents apresents a
standardized form that the user completesstandardized form that the user completes
so the system can generate a true query.so the system can generate a true query.

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Figure 6.16 Report of DepartmentsFigure 6.16 Report of Departments

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Structured Query LanguageStructured Query Language
►Structured query language (SQL)Structured query language (SQL) isis
the code that RDBMSs use to perform theirthe code that RDBMSs use to perform their
database tasks.database tasks.
►Method of choice for interacting with web-Method of choice for interacting with web-
based databases.based databases.
►Writing SQL statements are not difficult forWriting SQL statements are not difficult for
most manager’s data needs.most manager’s data needs.

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Figure 6.20 SQL CodeFigure 6.20 SQL Code

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Advanced Database ProcessingAdvanced Database Processing
► On-line analytical processing (OLAP)On-line analytical processing (OLAP) allowsallows
data analysis similar to statistical cross-tabulation.data analysis similar to statistical cross-tabulation.
► Data miningData mining,, data martsdata marts, &, & data warehousingdata warehousing
focus on methodologies that offer users quickfocus on methodologies that offer users quick
access to aggregated data specific to theiraccess to aggregated data specific to their
decision-making needs.decision-making needs.
► Knowledge discoveryKnowledge discovery analyzes data usage &analyzes data usage &
data commonality among different tables.data commonality among different tables.

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Database PersonnelDatabase Personnel
►Database Administrator (DBA)Database Administrator (DBA) is anis an
expert in developing, providing, andexpert in developing, providing, and
securing databases; duties includesecuring databases; duties include
 Database planning;Database planning;
 Database implementation;Database implementation;
 Database operation;Database operation;
 Database security.Database security.

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Database Personnel (Cont’d)Database Personnel (Cont’d)
►Database programmerDatabase programmer writes code towrites code to
strip and/or aggregate data from thestrip and/or aggregate data from the
databasedatabase
 High level of specialization & selectionHigh level of specialization & selection
►End userEnd user generates reports & forms, postgenerates reports & forms, post
queries to the database, & use results fromqueries to the database, & use results from
their database inquiries to make decisionstheir database inquiries to make decisions
that affect the firm & its environmentalthat affect the firm & its environmental
constituents.constituents.

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DBMSs in PerspectiveDBMSs in Perspective
►DBMS AdvantagesDBMS Advantages
 Reduce data redundancy.Reduce data redundancy.
 Achieve data independence.Achieve data independence.
 Retrieve data & information rapidly.Retrieve data & information rapidly.
 Improve security.Improve security.
►DBMS DisadvantagesDBMS Disadvantages
 Obtain expensive software.Obtain expensive software.
 Obtain a large hardware configuration.Obtain a large hardware configuration.
 Hire and maintain a DBA staff.Hire and maintain a DBA staff.