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IMS1907 Database Systems
Summer Semester 2004/2005
Lecture 1
Introduction to Database SystemsFundamentals and Concepts
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People
Lecturer– David Grant– Phone 9903 1064– david.grant@infotech.monash.edu.au
Tutors– Reagan Low– Arvind Arcot
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Resources
www.sims.monash.edu.au/subjects/IMS1907/index.htmlwww.sims.monash.edu.au/resources/assessment.html
Required text book– Hoffer, J.A., Prescott, M.B. and McFadden, F.R.,
(2002), (7th edn.), Modern Database Management, Pearson Education Inc., Upper Saddle River, NJ, USA.
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Unit Structure
1 x 2 hour lecture per day for 13 days1 x 2 hour laboratory/tutorial per day– tutorial exercises– unit test preparation
Two unit tests together worth 20% each– Microsoft Access, SQL
One final examination, 3 hours, worth 60%
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Inescapable TruthsLecturers do not really teach you anything, they present you with toolkits and informationThe overheads are a guide to points of discussion - they do not contain the total wisdom on any given topicThey identify and discuss the topics and issues you need to consider and understand when using the toolsYou learn by your own efforts at reading, comprehending, discussing and doing – this is a technical subject!Your assessed outcomes, generally, are directly proportional to your effort - you make yourself more equal!
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Database Systems TopicsIntroduction. database fundamentals and conceptsData modellingRelational theoryNormalisationSQLDatabase systems developmentDatabase design and optimisationData warehouses, OODBMS, internet DBsDatabase systems and organisations - roles of DA, DBA
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What are Database Systems?Many different types of information systems– TPS, GIS, MIS, DSS, EIS, KBS, expert, messaging,
HRIS, SIS, enterprise…..…used IS in many business areas to perform many functions– banking, airlines, universities, credit cards, finance,
telecommunications, sales, manufacturing, HRAlmost all of these rely on a database in some wayIn fact, database systems are at the heart of most information systems
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The amount of information being collected and stored is almost beyond comprehension – and its growingStored information is being used for more purposes than were conceivable ten (or even five) years agoDatabases are used at every level of society– individuals, small business, national organisations,
global corporations, governments…They affect many aspects of our everyday lives
Impact of Database Systems
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Databases are used in– monitoring and improving business operations– tracking customers and their behaviour– tracking and despatching emergency service vehicles– monitoring communications with space vehicles– making decisions (business and otherwise)– generating spam– performing surgical procedures– many other applications from the mundane to
miraculous
Impact of Database Systems
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Critical to business productivity and profitabilityCritical to individual life and safetyInstrumental in economic and social stabilityCan affect governmentsIt essential that information is accurate, up-to-date and consistentNot always easy when there are so many databases of so many types storing different versions of similar or the same information
Impact of Database Systems
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A Brief History of Database Systems
3000BC(?) knotted and coloured string, marks on clay
2000BC(?) papyrus-based recording
200BC(?) paper-based technologies
1950 file processing systems
1970 hierarchical DBMS,network DBMS (first generation DBMS), Codd’s relational model
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A Brief History of Database Systems
1980 relational DBMS (second generation DBMS), SQL
1990 internet, data warehouses, object-oriented DBMS, distributed databases
2000+ more complex data structures, universal servers, centralised databases, content-addressable storage, AI, data mining, mobile technologies, super computers…
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Basic Concepts
Central concepts for understanding database systems– Database– Data– Information– Data vs Information– Metadata– DBMS
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Database
An organised collection of logically related dataHas some inherent meaningRepresents some aspect of the real world (UoD)Vary in size and complexity (MB TB)Designed, built, and populated with data for a specific purpose and for intended usersGenerated and maintained manually or computerised
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Data
Traditionally referred to facts about things and events that could be recorded and stored (…on computer media)Referred to as structured dataData types are numeric, characters, datesStored as records in files (older) or more commonly in tabular form (tables, relations, arrays, spreadsheets, etc)
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Data
Traditional definition does not reflect current reality– structured data is the not the only type stored
Documents, images, sound, videoUnstructured data or multimedia data– “…stored representations of objects and events
that have meaning and importance in the users environment.”
Multimedia environments store and display structured and unstructured data
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Data vs Information
The terms data and information are often used interchangeably but it is useful to distinguish between themInformation– “…data that have been processed in such a way that
the knowledge of the person who uses the data is increased.”
– data with a context and other associated useful data– often summarised or otherwise-processed data that is
presented for interpretation
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Metadata
“…data that describe the properties or characteristics of end user data and the context of that data.”Data names, definitions, length/size, allowable valuesData source, storage location, stewardship, usageData about data – once removed from the dataEnables users and designers to understand what data exists, what it means – avoid errors, misinterpretationStored in the system catalog
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Database Management System (DBMS)
“…a software system that is used to create, maintain, and provide controlled access to user databases.”A general purpose set of software tools that facilitates the process of defining, constructing and manipulating data in a database for some specific purpose in a known contextProvides systematic method for creating, updating, storing and retrieving data in a database
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Data sharing between end users and programmersData sharing across multiple applicationsData access control, data integrity enforcement, concurrency control, restoration MS Access, MS SQL Server, Oracle, MySQL, Informix, DB2, Teradata, Ingres, SyBaseObjectivity, Cache, Gemstone, Jasmine, O2, ObjectStore, POET, Versant
Database Management System (DBMS)
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DBMS vs File Processing SystemsTraditional File Processing systems had disadvantages– program-data dependence– data duplication, inconsistency– integrity problems– hard to access– atomicity, concurrency, security problems– limited data sharing– lengthy development times– excessive program maintenance
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DBMS vs File Processing Systems
DBMS provide benefits when compared to traditional File Processing systems – program-data independence– minimal data redundancy - controlled– improved data consistency– improved data sharing – improved access and security controls– increased productivity of application development
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DBMS vs File Processing Systems
DBMS benefits– enforcement of standards– improved data quality– improved data accessibility and responsiveness– reduced program maintenance– improved decision support– persistent storage for application objects and data
structures
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DBMS vs File Processing Systems
DBMS benefits– rule-based inferencing and actions– multiple user interfaces– multi-user transaction processing– represent complex data relationships– enforce integrity constraints– backup and recovery
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A database system contains– DBMS– database– metadata (repository)
Also in the database system environment are– application software– CASE tools– user interfaces– users, developers, administrators
What are Database Systems?
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Database SystemsUsers/developers
Application programs/queries
Software to process queries/programs
Software to access stored data
DATABASE SYSTEM
DBMS
Metadata Database
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Database Systems
DBMSMetadata Database
CASEtools
Application programs
User interfaces
End usersSystem
developersData and database
administrators
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Personal DatabasesWorkgroup DatabasesDepartment DatabasesEnterprise DatabasesInternet, Intranet, and Extranet DatabasesData warehouses
Types of Database Systems
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Need for new, specialised personnelInstallation cost and complexityMaintenance cost and complexityConversion costs from legacy systemsCritical need for explicit backup and recoveryOrganisational conflict and change
Costs and Risks of Database Systems
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An organisation’s success or failure can depend on the accuracy and availability of its informationAn expensive pause… (source: Standish Group)
Database Systems and Organisations
ApplicationCost of
downtime/minute @ normal load
Cost of downtime/minute @
peak load
CRM $2,200 $2,500
Data Warehouse $5,800 $6,300
Electronic Commerce
$2,500 $7,800
ERP $6,400 $7,900
SCM $4,400 $6,600
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What databases have you been in contact with this week? (directly and indirectly)What databases are you on that you know about?What databases do you think you might be on that you don’t know about?How important is it that you are on at least some databases?
Database Systems and You
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Hoffer et al, Chapter 2
Reading for Next Week
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References
Elmasri, R. and Navathe, S.B., (2000), (3rd edn.), Fundamentals of Database Systems, Addison-Wesley, Reading, Massachusetts, USA.
Hoffer, J.A., Prescott, M.B. and McFadden, F.R., (2002), (7th edn.), Modern Database Management, Pearson Education Inc., Upper Saddle River, NJ, USA.
Murphy, B., (1999), Data Downtime Dilemma, accessed 5th July 2004 at http://www.findarticles.com/p/articles/mi_m0SMG/is_3_19/ai_59329322.
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