IMS1907 Database Systems

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

2. People • Lecturer • David Grant • Phone 9903 1064 • david.grant@infotech.monash.edu.au • Tutors • Reagan Low • Arvind Arcot Monash University 2004

3. Resources • www.sims.monash.edu.au/subjects/IMS1907/index.html • www.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. Monash University 2004

4. Unit Structure • 1 x 2 hour lecture per day for 13 days • 1 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% Monash University 2004

5. Inescapable Truths • Lecturers do not really teach you anything, they present you with toolkits and information • The overheads are a guide to points of discussion - they do not contain the total wisdom on any given topic • They identify and discuss the topics and issues you need to consider and understand when using the tools • You 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! Monash University 2004

6. Database Systems Topics • Introduction. database fundamentals and concepts • Data modelling • Relational theory • Normalisation • SQL • Database systems development • Database design and optimisation • Data warehouses, OODBMS, internet DBs • Database systems and organisations - roles of DA, DBA Monash University 2004

7. 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, HR • Almost all of these rely on a database in some way • In fact, database systems are at the heart of most information systems Monash University 2004

8. Impact of Database Systems • The amount of information being collected and stored is almost beyond comprehension – and its growing • Stored information is being used for more purposes than were conceivable ten (or even five) years ago • Databases are used at every level of society • individuals, small business, national organisations, global corporations, governments… • They affect many aspects of our everyday lives Monash University 2004

9. 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 Monash University 2004

10. Impact of Database Systems • Critical to business productivity and profitability • Critical to individual life and safety • Instrumental in economic and social stability • Can affect governments • It essential that information is accurate, up-to-date and consistent • Not always easy when there are so many databases of so many types storing different versions of similar or the same information Monash University 2004

11. A Brief History of Database Systems Monash University 2004

12. A Brief History of Database Systems Monash University 2004

13. Basic Concepts • Central concepts for understanding database systems • Database • Data • Information • Data vs Information • Metadata • DBMS Monash University 2004

14. Database • An organised collection of logically related data • Has some inherent meaning • Represents 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 users • Generated and maintained manually or computerised Monash University 2004

15. Data • Traditionally referred to facts about things and events that could be recorded and stored (…on computer media) • Referred to as structured data • Data types are numeric, characters, dates • Stored as records in files (older) or more commonly in tabular form (tables, relations, arrays, spreadsheets, etc) Monash University 2004

16. Data • Traditional definition does not reflect current reality • structured data is the not the only type stored • Documents, images, sound, video • Unstructured 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 Monash University 2004

17. Data vs Information • The terms data and information are often used interchangeably but it is useful to distinguish between them • Information • “…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 Monash University 2004

18. Metadata • “…data that describe the properties or characteristics of end user data and the context of that data.” • Data names, definitions, length/size, allowable values • Data source, storage location, stewardship, usage • Data about data – once removed from the data • Enables users and designers to understand what data exists, what it means – avoid errors, misinterpretation • Stored in the system catalog Monash University 2004

19. 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 context • Provides systematic method for creating, updating, storing and retrieving data in a database Monash University 2004

20. Database Management System (DBMS) • Data sharing between end users and programmers • Data sharing across multiple applications • Data access control, data integrity enforcement, concurrency control, restoration • MS Access, MS SQL Server, Oracle, MySQL, Informix, DB2, Teradata, Ingres, SyBase • Objectivity, Cache, Gemstone, Jasmine, O2, ObjectStore, POET, Versant Monash University 2004

21. DBMS vs File Processing Systems • Traditional 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 Monash University 2004

22. 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 Monash University 2004

23. 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 Monash University 2004

24. 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 Monash University 2004

25. What are Database Systems? • A database system contains • DBMS • database • metadata (repository) • Also in the database system environment are • application software • CASE tools • user interfaces • users, developers, administrators Monash University 2004

26. Users/developers DATABASE SYSTEM Application programs/queries DBMS Software to process queries/programs Software to access stored data Database Metadata Database Systems Monash University 2004

27. Data and database administrators System developers End users CASE tools User interfaces Application programs DBMS Database Metadata Database Systems Monash University 2004

28. Types of Database Systems • Personal Databases • Workgroup Databases • Department Databases • Enterprise Databases • Internet, Intranet, and Extranet Databases • Data warehouses Monash University 2004

29. Costs and Risks of Database Systems • Need for new, specialised personnel • Installation cost and complexity • Maintenance cost and complexity • Conversion costs from legacy systems • Critical need for explicit backup and recovery • Organisational conflict and change Monash University 2004

30. Database Systems and Organisations • An organisation’s success or failure can depend on the accuracy and availability of its information • An expensive pause… (source: Standish Group) Monash University 2004

31. Database Systems and You • 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? Monash University 2004

32. Reading for Next Week • Hoffer et al, Chapter 2 Monash University 2004

33. 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. Monash University 2004