44220: Database Design & Implementation Introduction to Module Ian Perry Room: C49 Ext.:

Ian PerrySlide : Database Design & Implementation: Introduction to Module The Structure of the Module Database Design & Implementation is concerned with three things: Why data storage (and information retrieval) needs to be organised in some manner. How such a data storage system might be designed in such a way that it is demonstrably robust. How such a design might be implemented using a Relational DataBase Management System (RDBMS).

Ian PerrySlide : Database Design & Implementation: Introduction to Module Lectures & Workshops Mon, 1:15 (CG7) Tue, 11:15 (IT4) 18. Introduction to Module 19. Modelling the ‘Real’ World 20. Conceptual Data Modelling 21. ER Diagramming 22. Logical Data Modelling 23. Avoiding Data Anomalies 24. Review & Ass 1 Reqs. 18. Information For All? 19. Modelling Exercises 20. Conceptual Modelling Ex. 21. Drawing ER Diagrams 22. Logical Modelling - Part Logical Modelling - Part Assignment 1 Support 26. Physical Data Modelling 27. Implementing Domains 28. Review & Ass 2 Reqs No Lecture MS Access – Workshop MS Access – Workshop Assignment 2 Support 29. Assignment 2 Support [ Ass 1 Deadline – 01 Mar ] [ Ass 2 Deadline – 28 Apr ] Easter Break

Ian PerrySlide : Database Design & Implementation: Introduction to Module Assessment – based on a Case Study Learn-By-Post … handles the assessment and examination of students who are taking modules by mail order. There are currently 12 modules on offer (there are plans to increase this number to 18); with each student taking a maximum of 3 modules per year. Each module takes one year to complete, at the end of which an examination is taken at one of five examination centres around the country. Read the Case Study Carefully There is a lot more to it than you might think initially. It would, therefore, pay you to re-read it from time to time. Your database ‘solutions’ must be able to ‘answer’ 10 specific questions, e.g.: Who are our students? What is the assessment/examination weighting for all of the available modules? Which students should be sent a certificate for module X? Etc.

Ian PerrySlide : Database Design & Implementation: Introduction to Module Two Assignments Assignment 1 (50%) – 01 March 2006 Develop and document an appropriate Conceptual Data Model. Develop and document a robust Logical Data Model. Assignment 2 (50%) – 28 April 2006 Implement your logical database model as a Physical Data Model, using Microsoft Access. Test this physical data model by building a number of Database Queries, to make sure that it ‘ works ’.

Ian PerrySlide : Database Design & Implementation: Introduction to Module Data & Information Data? A series of observations, measurements, or facts. Information? Data that have been transformed into a meaningful and useful form for people. Process DataInformation (perhaps!)

Ian PerrySlide : Database Design & Implementation: Introduction to Module Information Attributes Information (or do I mean data?) can be thought of as having three dimensions: Time Timeliness, Currency, Frequency, etc. Content Accuracy, Relevance, Completeness, etc. Form Clarity, Detail, Order, Presentation, etc. Information is often affected by more than one of the above.

Ian PerrySlide : Database Design & Implementation: Introduction to Module Information = ? Structure & Context People tend to look for a familiar structure & place data in a familiar context, e.g.: : => DD/MM/YY = 12/05/06 = 12 May We use structure & context to transform the data we receive into information. Information = Data + Structure + Context The same data can be ‘interpreted’ as different information if a different structure and/or context is applied.

Ian PerrySlide : Database Design & Implementation: Introduction to Module To sum up so far! Data  Information. Data are simply facts relating to ‘things’ like events, transactions, etc. Information is a people thing, only they can: determine the structure & context with which data might become information. and make decisions based upon the knowledge gained by the possession of that information. Must understand the difference between Data & Information: in order to Design & Implement a Database System that is both Efficient & Effective.

Ian PerrySlide : Database Design & Implementation: Introduction to Module Traditional Data Storage Computing has often been introduced to organisations in piecemeal manner. With the addition of each new software application comes the need to create a new set of files; containing that application’s required records. with each record containing that application’s required fields. and each field storing an ‘important’ data item. Over time the same data items will tend to be stored again and again (and again?) in the file systems of multiple applications: which leads to a number of problems!

Ian PerrySlide : Database Design & Implementation: Introduction to Module Data Redundancy The repetition, in two or more files, of the same data item. There are an uncontrolled number of copies, which is: Expensive in Storage Expensive in Time

Ian PerrySlide : Database Design & Implementation: Introduction to Module Data Inconsistency The problem of version control. With many versions of the data likely: Which one is the most up to date? Which one should I believe? Destroys user confidence. Very confusing. Potentially very expensive.

Ian PerrySlide : Database Design & Implementation: Introduction to Module Data Dependence Applications and their data are ‘bound’ (i.e. stored) together. This doesn’t represent the way business organisations need to use data. The road to ‘information’ is impeded by the binding ‘glue’.

Ian PerrySlide : Database Design & Implementation: Introduction to Module Data Sequencing If (when?) we need to combine the data from two, or more, business areas then the physical HOWs can be complex. Which often requires complicated patching systems; in order to: extract the data from one system. enter that data into the next. In extreme cases this may mean: printing out the data from one system. manually re-entering it into the next.

Ian PerrySlide : Database Design & Implementation: Introduction to Module A Database Approach Take a holistic view of an organisation’s information requirements, so that: data is thought of as a pivotal, company wide, resource. Laying a foundation of: shared, common, data in which all have confidence. with well maintained & controlled access to that data. In other words: a Database!

Ian PerrySlide : Database Design & Implementation: Introduction to Module Definitions A database is: an organised collection of data. A database management system (DBMS) is: software designed to assist in maintaining and utilising large collections of data. A relational database management system (RDBMS) is: a specific type of DBMS.

Ian PerrySlide : Database Design & Implementation: Introduction to Module What does a RDBMS do? Main Features: Data is stored independently of the means of data manipulation. Data addition, alteration, retrieval are all controlled, consistent tasks. Different users see different data collections. Which gives us some advantages, i.e.: Minimal Data Redundancy (+ Data Consistency) Data Independence (+ Data Flexibility) Data Sharing (+/- Data Security)

Ian PerrySlide : Database Design & Implementation: Introduction to Module Why should we care? “Data is only potential information; information is potential knowledge; and knowledge is potential competitive advantage if it is used in a creative, flexible, and above all, accurate way.” Adrian M (1990) Let’s Get Serious. Focus News. Winter.