IMS1907 Database Systems Summer Semester 2004/2005 Lecture 1 Introduction to Database Systems Fundamentals and Concepts

IMS1907 Database Systems

Summer Semester 2004/2005

Lecture 1

Introduction to Database SystemsFundamentals and Concepts

Monash University 2004 2

People

Lecturer– David Grant– Phone 9903 1064– [email protected]

Tutors– Reagan Low– Arvind Arcot

mailto:[email protected]


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.

http://www.sims.monash.edu.au/subjects/IMS1907/index.html

http://www.sims.monash.edu.au/subjects/IMS1907/index.html

http://www.sims.monash.edu.au/resources/assessment.html

http://www.sims.monash.edu.au/resources/assessment.html


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%


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!


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


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


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


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



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



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


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…


Basic Concepts

Central concepts for understanding database systems– Database– Data– Information– Data vs Information– Metadata– DBMS


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


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)


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


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


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


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


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)


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


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



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



DBMS benefits– rule-based inferencing and actions– multiple user interfaces– multi-user transaction processing– represent complex data relationships– enforce integrity constraints– backup and recovery


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?


Database SystemsUsers/developers

Application programs/queries

Software to process queries/programs

Software to access stored data

DATABASE SYSTEM

DBMS

Metadata Database


Database Systems

DBMSMetadata Database

CASEtools

Application programs

User interfaces

End usersSystem

developersData and database

administrators


Personal DatabasesWorkgroup DatabasesDepartment DatabasesEnterprise DatabasesInternet, Intranet, and Extranet DatabasesData warehouses

Types of Database Systems


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


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


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


Hoffer et al, Chapter 2

Reading for Next Week


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.