Beginning Database Design ppt

[...]... improved database design for the insect problem Designing for a Single Report Another cause of a problematic database is to design a table to match the requirements of a particular report A small business might have in mind a format that is required for an invoice A school secretary may want to see the whereabouts of teachers during the week Thinking backward from one specific report can lead to a database. .. would have been avoided Summary The first thoughts about how to design a database may be influenced by a particular report or by a particular method of input Sometimes the driver for a database is simply that some valuable information has come to hand and needs to be “put somewhere.” The hurried creation of a database or spreadsheet can lead to a design that cannot cope with even simple changes to the information... sufficient Here is a brief overview of how the design might be done in a relational database We consider the details more thoroughly in Chapters 7 to 9, so if you don’t follow all the reasoning here, don’t panic For those readers who already know something about database design, please excuse the simplifications In very broad terms, each class will be represented by a database table Because each species can... and create an appropriate design For a relational database, this will involve designing tables, keys, and foreign keys Different structures will be required if the project is to be implemented in some other type of product such as a programming language or a spreadsheet The design phase is discussed more fully in Chapters 7 to Chapter 9 4 Build the application For a relational database, this will include... the underlying data, and design the database to reflect the information being stored rather than what you might want to do with the data in the short term 7 CHAPTER 1 ■ What Can Go Wrong Testing Your Understanding Exercise 1-1 A school is planning some outdoor activities for its students The staff wants to create a database of how parents can help The secretary sets up the database table in Figure 1-7... Problem statement Abstract world Model design Solution Application Software design implementation Figure 2-1 The software process (based on Zelkowitz et al., 19791) Using Figure 2-1 as a way of thinking about software processes, we will now look at how the various steps relate to setting up a database project by applying those steps to Example 1-1, “The Plant Database. ” Initial Problem Statement We... will eventually be implemented You may be designing your own database, or perhaps you are designing one for someone else In either case, there are two views of the problem One is the concrete, real-world view from the person who will be the eventual user (I will call this person the client), and the other view is the more abstract model from the person who is designing and possibly developing the system... where we started with an initial database table recording plants and their uses Figure 2-3 Original data of plants and uses If we consider what typical people might want to do with the data shown in Figure 2-3, the use cases suggested in Example 2-1 would be a start Example 2-1 Initial use Cases for the Plant Database Figure 2-4 shows some initial use cases for the plant database The text following the... terms they use Design After a few iterations of evaluating the use cases and class diagrams, we should have an initial data model and a set of use cases that show in some detail how we intend to satisfy the requirements of the users The next stage is to consider what type of software would be suitable for implementing the project For a database project, we could choose to use a relational database product... several years’ worth of data were left in a state that no one else could comprehend And that’s how I got my first database job (and the database coped with changing requirements over several years) Example 1-4 is particularly good for showing how much trouble you can get into with a poor design The developer could see the problem from the point of view of the required report He thought in terms of one . model into a database design. You’ll learn to design better databases. You’ll avoid the cost of “getting it wrong.” Create a Data Model e chasm between having a basic idea of what your database. decide on the best database design to support that. Jumping ahead a bit to see a solution for the plant database problem, you can quite quickly set up a useful relational database by creating. Table Visits Table Counts Figure 1-5. An improved database design for the insect problem CHAPTER 1 ■ WHAT CAN GO WRONG 7 A database table was designed to exactly match the report in Figure 1-6,