Database Design
Overview
Nobody ever writes a database twice. The design decisions made in the first hour, which tables exist, what each field holds and which field identifies a record, are the ones everything afterwards is built on, and they are the ones that are painful to change once there is real data in the system. Getting them right is a skill, and it is a skill made of three specific choices rather than of general good taste.
This lesson teaches those three choices: picking an appropriate data type, and a length where a length is called for; selecting a suitable primary key; and turning a paragraph describing a situation into a set of linked tables. You will also learn the exact notation this specification uses to write a design down, which is worth knowing precisely, because a design written in the expected form is quick to mark and a design sketched informally is not.
Objectives
- Be able to choose appropriate data types and (where appropriate) lengths for fields in a table. Be able to select a suitable primary key for a table. Be able to produce a design for a relational database from a description of a scenario.
Mind map
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Database Design. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Which data type is most appropriate for a field storing a telephone number? A. Integer B. Real C. String D. Boolean Answer: C
- For which of these fields is it appropriate to give a length? A. A Boolean field recording whether a fee has been paid B. A string field holding a surname C. An integer field holding a quantity D. A real field holding a price Answer: B
- In the notation used by this specification, how is the primary key of a table indicated? A. It is written in capital letters B. It is underlined C. It is placed in square brackets D. It is written last in the list Answer: B
- One member may make many bookings, and each booking is made by one member. Where should the foreign key be placed? A. In the Member table B. In the Booking table C. In both tables D. In neither table Answer: B
- What is the maximum number of tables the specification says an examined design scenario will require? A. Two B. Three C. Four D. There is no limit Answer: B
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Work through these questions in the app
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