2. Introduction to DBMS
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Transcript of 2. Introduction to DBMS
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Introduction to Databaseana emen ys em
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ObjectivesObjectives Define termsDefine terms
Name limitations of conventional file processingName limitations of conventional file processing Explain advantages of databasesExplain advantages of databases
Identify costs and risks of databasesIdentify costs and risks of databases
List components of database environmentList components of database environment en y ca e or es o a a ase app ca onsen y ca e or es o a a ase app ca ons
Describe database system development life cycleDescribe database system development life cycle
Explain roles of individualsExplain roles of individuals
Ex lain the threeEx lain the three--schema architecture for databasesschema architecture for databases
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DefinitionsDefinitions Data ase:Data ase:
Organized collection of logically related dataOrganized collection of logically related data
Stored representations of meaningful objects andStored representations of meaningful objects and
eventsevents
Structured:Structured:
Numbers, text, datesNumbers, text, dates
Images, video, documentsImages, video, documents
Information:Information:
Data processed to increase knowledge in the personData processed to increase knowledge in the personusing the datausing the data
e a a a:e a a a:
Data that describes the properties and context of userData that describes the properties and context of userdatadata
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Context helps users understand data
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Summarized data
Graphical displays turn data into usefulinformation that managers can use for
decision making and interpretation
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Descriptions of the properties or characteristics of thedata, including data types, field sizes, allowable
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Disadvantages of File ProcessingDisadvantages of File Processing
ProgramProgram--Data DependenceData Dependence All programs maintain metadata for each file they useAll programs maintain metadata for each file they use
Duplication of DataDuplication of Data Different systems/programs have separate copies of the same dataDifferent systems/programs have separate copies of the same data
No centralized control of dataNo centralized control of data
Programmers must design their own file formatsProgrammers must design their own file formats
Excessive Pro ram MaintenanceExcessive Pro ram Maintenance 80% of information systems budget80% of information systems budget
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ro ems w a a epen encyro ems w a a epen ency Each application programmer must maintainEach application programmer must maintain
his/her own datahis/her own data Each application program needs to includeEach application program needs to include
Each application program must have its ownEach application program must have its own
updating, and deleting dataupdating, and deleting data
Lack of coordination and central controlLack of coordination and central control
NonNon--standard file formatsstandard file formats
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Problems with Data RedundancyProblems with Data Redundancy
Waste of space to have duplicate dataWaste of space to have duplicate data
auses more ma n enance ea ac esauses more ma n enance ea ac es
The bi est roblem:The bi est roblem: Data changes in one file could causeData changes in one file could cause
Compromises inCompromises in dat a int egr i t ydat a int egr i t y
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SOLUTION:SOLUTION:
e pproace pproac
Data is managed by a controllingData is managed by a controllingagenagen
Stored in a standardized convenientStored in a standardized convenient
formform
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A software system that is used to create, maintain, and provide
controlled access to user databases
Order FilingSystem
Invoicing
System DBMS
Central database
Payroll
,order, inventory,
pricing, andcustomer data
manages a a resources e an opera ng sys em manages ar wareresources
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vantages o t e ata asevantages o t e ata ase
A roachA roach ProgramProgram--data independencedata independence Planned data redundancyPlanned data redundancy
Improved data consistencyImproved data consistency
Improved data sharingImproved data sharing
Enforcement of standardsEnforcement of standards
Improved data accessibility and responsivenessImproved data accessibility and responsiveness
Reduced program maintenanceReduced program maintenance
Improved decision supportImproved decision support
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Costs and Risks of the DatabaseCosts and Risks of the Database
,,
Installation and management cost andInstallation and management cost and
Conversion costsConversion costs
The change managementThe change management
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Elements of the DatabaseElements of the Database
Data modelsData models Graphical system capturing nature and relationship of dataGraphical system capturing nature and relationship of data
the organizationthe organization
Project Data ModelProject Data Model more detailed view, matching datamore detailed view, matching datastructure in database or data warehousestructure in database or data warehouse
EntitiesEntities Noun form describing a person, place, object, event, or conceptNoun form describing a person, place, object, event, or concept
Composed of attributesComposed of attributes
RelationshipsRelationships Between entitiesBetween entities
Usually oneUsually one--toto--many (1:M) or manymany (1:M) or many--toto--many (M:N)many (M:N)
Relational DatabasesRelational Databases
Database technology involving tables (relations) representingDatabase technology involving tables (relations) representingentities and primary/foreign keys representing relationshipsentities and primary/foreign keys representing relationships
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Segment of an enterprise data model
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One customer
may place many
orders, but each
order is placed by
a sin le customer
One-to-many
relationshi
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One order has
many or er nes;
each order line is
associated with a
single order
One-to-many
relationship
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One product can
order lines, each
order line refers
to a single
product
ne- o-many
relationship
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,
order involvesmany products
and one product is
involved in many
orders
Many-to-many
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Components of the Database Environment
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omponents o t eomponents o t eDatabase EnvironmentDatabase Environment
CASE ToolsCASE Toolscomputercomputer--aided software engineeringaided software engineering RepositoryRepositorycentralized storehouse of metadatacentralized storehouse of metadata
Database Management System (DBMS)Database Management System (DBMS) software forsoftware formanaging the databasemanaging the database
Application ProgramsApplication Programssoftware using the datasoftware using the data
User InterfaceUser Interfacetext and graphical displays to userstext and graphical displays to users
a a a a ase m n s ra orsa a a a ase m n s ra orspersonne respons epersonne respons efor maintaining the databasefor maintaining the database
System DevelopersSystem Developerspersonnel responsible forpersonnel responsible fores gn ng a a ases an so warees gn ng a a ases an so ware
End UsersEnd Userspeople who use the applications andpeople who use the applications anddatabasesdatabases
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The Range of Database ApplicationsThe Range of Database Applications
Personal databasesPersonal databases
TwoTwo--tier Client/Server databasestier Client/Server databases
Enterprise applicationsEnterprise applications
Data warehousing implementationsData warehousing implementations
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Two-tier database with local
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Three-tiered client/server database architecture
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Enterprise Database ApplicationsEnterprise Database Applications
Enter rise Resource Plannin ERPEnter rise Resource Plannin ERP
Integrate all enterprise functionsIntegrate all enterprise functions
(manufacturing, finance, sales, marketing,(manufacturing, finance, sales, marketing,inventory, accounting, human resources)inventory, accounting, human resources)
Data WarehouseData Warehouse
Integrated decision support system derived fromIntegrated decision support system derived fromvarious operational databasesvarious operational databases
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Evolution of database technologies
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wo pproac es to ata ase anwo pproac es to ata ase anIS Develo mentIS Develo ment
SDLCSDLC System Development Life CycleSystem Development Life Cycle
Detailed, wellDetailed, well--planned development processplanned development process
TimeTime--consuming, but comprehensiveconsuming, but comprehensive
PrototypingPrototyping Rapid application development (RAD)Rapid application development (RAD)
Cursory attempt at conceptual data modelingCursory attempt at conceptual data modeling Define database during development of initialDefine database during development of initial
Repeat implementation and maintenance activitiesRepeat implementation and maintenance activitieswith new prototype versionswith new prototype versions
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Systems Development Life CycleSystems Development Life Cycle
Planning
Logical Design
Physical Design
Implementation
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Systems Development Life CycleSystems Development Life Cycle
(cont.)(cont.)Pur ose reliminar understandin
Analysis
Deliverablerequest for study
Logical Design
Physical Design
Database activit
Maintenance
enterprise modeling andearly conceptual data
modeling
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Systems Development Life CycleSystems Development Life Cycle
(cont.)(cont.)Purposethorough requirements analysis and
AnalysisAnalysis
structur ng
Deliverablefunctional system specifications
Logical Design
Physical Design
Database activit thorou h
Maintenance
and integrated conceptualdata modeling
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Systems Development Life CycleSystems Development Life Cycle
(cont.)(cont.)Purposeinformation requirements elicitation
Analysis
Deliverabledetailed design specifications
Logical DesignLogical Design
Physical Design
Database activit
Maintenance
logical database design(transactions, forms,
displays, views, data
integrity and security)
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Systems Development Life CycleSystems Development Life Cycle
(cont.)(cont.)Purposedevelop technology and
organizational specifications
AnalysisDeliverableprogram/datastructures, technology purchases,
Logical Design
organization redesigns
Physical DesignPhysical Design
Database activit
Maintenance
physical database design (definedatabase to DBMS, physical
data organization, database
processing programs)
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Systems Development Life CycleSystems Development Life Cycle
(cont.)(cont.)Purposeprogramming, testing,
Analysis
, ,
Deliverableoperational programs,
Logical Design
Physical Design
Database activity
Maintenance
a a ase mp emen a on,
including coded programs,
documentation,
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Systems Development Life CycleSystems Development Life Cycle
(cont.)(cont.)Purposemonitor, repair, enhance
AnalysisDeliverableperiodic audits
Logical Design
Physical Design
Database activity
MaintenanceMaintenance
a a ase ma n enance,
performance analysis
and tuning, error
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Prototyping Database MethodologyPrototyping Database Methodology
P t t i D t b M th d lP t t i D t b M th d l
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Prototyping Database MethodologyPrototyping Database Methodology
..
P t t i D t b M th d lP t t i D t b M th d l
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Prototyping Database MethodologyPrototyping Database Methodology
..
Prototyping Database MethodologyPrototyping Database Methodology
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Prototyping Database MethodologyPrototyping Database Methodology
cont.cont.
Prototyping Database MethodologyPrototyping Database Methodology
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Prototyping Database MethodologyPrototyping Database Methodology
..
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Managing ProjectsManaging Projects Pro ectPro ecta lanned undertakin of relateda lanned undertakin of related
activities to reach an objective that has aactivities to reach an objective that has abeginning and an endbeginning and an end
Validation of satisfactory progressValidation of satisfactory progress
Ste back from detail to overall viewSte back from detail to overall view Renew commitment of stakeholdersRenew commitment of stakeholders
Incremental commitmentIncremental commitmentreview of systemsreview of systems
eve opmen pro ec a er eaceve opmen pro ec a er eacdevelopment phase withdevelopment phase with rejustificationrejustification afteraftereach haseeach hase
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anag ng ro ec s: eop eanag ng ro ec s: eop eInvolvedInvolved Business analystsBusiness analysts
Systems analystsSystems analysts
Database analysts and data modelersDatabase analysts and data modelers
UsersUsers ProgrammersProgrammers
Database architectsDatabase architects
Data administratorsData administrators
Other technical expertsOther technical experts
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Terminology
Relation
Attribute
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Database SchemaDatabase Schema External SchemaExternal Schema User ViewsUser Views
Subsets of Conceptual SchemaSubsets of Conceptual Schema
an e e erm ne rom us nessan e e erm ne rom us ness-- unc on a aunc on a aentity matricesentity matrices
DBA determines schema for different usersDBA determines schema for different users Conceptual SchemaConceptual Schema
Internal SchemaInternal Schema
Three-schema architecture
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Different people
have different
databasethese
are the external
The internal
schema is the
underlying
implementation
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Enterprise Data ModelEnterprise Data Model
First step in database developmentFirst step in database development S ecifies sco e and eneral contentS ecifies sco e and eneral content
Overall picture of organizational data at highOverall picture of organizational data at high
level of abstractionlevel of abstraction EntityEntity--relationship diagramrelationship diagram
Descri tions of entit t esDescri tions of entit t es
Relationships between entitiesRelationships between entities