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Topic 09 : Database Design

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Topic 09 : Database Design

  1. 1. Er. Pradip Kharbuja Topic 9 Database Design
  2. 2. Systems Analysis & Development Systems Analysis The art of understanding and documenting the requirements of a given set of users within the context of an organization. Systems Development The development of the whole system from beginning to end. This might include a database, applications, a network etc.
  3. 3. Approaches to System Development There are many different approaches to systems development. 1.Traditional systems development lifecycle (SDLC) or ‘waterfall’ approach 2.Iterative approaches Understanding requirements is vital to being able to produce a finished system that meets the business needs of an organization.
  4. 4. Waterfall Approach Traditional systems development lifecycle (SDLC) Also known as Generic Systems Development Lifecycle This involves a complete set of steps that a team follows. The fundamental idea is to divide the development process into a series of phases or stages, each of which finishes before the next one starts. This process is often viewed as a cascade of steps, which is why it has been called the waterfall approach.
  5. 5. Waterfall Approach 1.Strategy and planning 2.Feasibility study 3.Systems analysis (or analysis) 4.Design 5.Implementation 6.Maintenance
  6. 6. Problems with Waterfall Approach Users have not communicated requirements properly Users have not understood their own needs Analyst misunderstood Omission
  7. 7. Prototypes and Prototyping Prototype –a first or original example of something from which others have or will be developed Prototyping –the process whereby a model is built of part of the envisaged system and user feedback on it is gathered. Part of the requirements gathering process Note: a prototype is a thing. Prototyping is something we do.
  8. 8. Iteration
  9. 9. Database Design Database Design means moving from a set of requirements to implementing these with database technology. Moving from a set of requirements Database Technology
  10. 10. Phases of Database Design Conceptual design Logical design Physical design
  11. 11. Conceptual Database Design Investigation of data needed to support system Design is undertaken without regard either to the physical implementation or data model. So the designers at this stage do not even assume they will be using the relational model. The sorts of areas of investigation are: what data does the enterprise hold? In what format is it? How is it used?
  12. 12. Logical Design Logical Database Design constructs the model without regard for the particular DBMS that will be used. However, the data model (e.g. the relational model) is known. A key activity is normalization. The output of logical design will be an Entity Relationship Model.
  13. 13. Physical Design The moving from entities to tables is one of the key activities here involving what is known as designing the base relations. But this phase also involves other activities, such as indexing, denormalization, view creation and query tuning.
  14. 14. Case Tools Computer Aided Software Engineering Design tools Documentation tools Code generators
  15. 15. ANY QUESTIONS? End of Topic -09

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