44220: Database Design & Implementation Introduction to Module Ian Perry Room: C41C Ext.:

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

Ian PerrySlide : Database Design & Implementation: Introduction to Module Lectures & Workshops Fri, 10:15 (C17a) Fri, 11:15 (IT3) 19. Introduction to Module 20. Modelling the ‘Real’ World 21. Conceptual Data Modelling 22. ER Diagramming 23. Logical Data Modelling 24. Avoiding Data Anomalies 19. Explore the DD&I Web-site 20. Modelling Exercises 21. Conceptual Modelling Ex. 22. Drawing ER Diagrams 23. Logical Modelling - Part Logical Modelling - Part Review & Ass 2 Reqs No Lecture – No Lecture – 30. Assignment 2 Support 31. Assignment 2 Support 32. Assignment 2 Support [ Ass 1 Deadline – Wednesday, 18 th of March ] [ Ass 2 Deadline – Wednesday, 13 th of May ] Easter Break Physical Data Modelling 29. Implementing Domains 28. MS Access – Workshop MS Access – Workshop 2

Ian PerrySlide : Database Design & Implementation: Introduction to Module Assessment – based on a Case Study Perry’s Newsagents Deliver a variety of Daily/Weekly/Monthly Newspapers and Magazines to a large number of customers in the town of Beverley (East Yorkshire). Read the Case Study Carefully There is a lot more to it than you might think initially; and don’t forget to re-read it from time to time. Your Role You have been asked take part in the development of a Database System for Perry’s Newsagents that can: record the Newspapers and/or Magazines supplied by specific Suppliers. record Customer Orders for Newspapers and/or Magazines. plan the Daily Delivery of Newspapers and Magazines to Customers. Your database ‘solution’ MUST be able to ‘answer’ 10 specific questions (i.e. at the end of the Case Study), e.g.: A.What Newspapers & Magazines do we sell? C.Which Newspapers & Magazines are supplied by Supplier X? F.Which Newspapers and Magazines has Customer X ordered?

Ian PerrySlide : Database Design & Implementation: Introduction to Module Two Assignments Assignment 1 (50%) – 18 th of March, 2009 Develop and document an appropriate Conceptual Data Model. Develop and document a robust Logical Data Model. Assignment 2 (50%) – 13 th of May, 2009 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 = 12/05/09 = 12 May 2009 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 (Ass 1) & Implement (Ass 2) a Database 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.