Year 12 > 13 Applied GCE ICT Unit 7 Using Database Software

Introduction to Unit 7 This unit goes into databases in a lot more detail than you have done previously You need to be able to plan and design an efficient database system in Microsoft Access to meet a given task. You need to know something about database theory and formal methods

Some Definitions What is a database ? What is a relational database ? What makes up a relational database ? –Entities>Tables –Attributes>Fields –Relationships>Links between tables

Lending Library Database Think of a lending library: What are the main entities involved ? What attributes does each entity have ? How are the entities linked together ?

Entity Relationship Diagrams (ERD) ERDs are used to plan and design large databases in order to make them efficient. BorrowersBooksLoans Name Address Date of Birth Book Title Author Subject Loan Date Date Due Back Borrower Book Title

Key Fields Each table in a database must have some way uniquely identifying each record This is usually done with a special field called the ‘Primary Key’, which is usually a number or combination of numbers and letters, and often has ID in the fieldname In a relational database, tables are linked together using these primary key fields

Other Key Fields A Primary Key can be made up of more than one field – this type is called a ‘Composite Key’ A Primary Key which appears as a ‘normal’ field in another table is called a ‘Foreign Key’

Primary Keys ERD with extra fields added: BorrowersBooksLoans BorrowerID Last Name First Name Date of Birth Address Postcode BookID Book Title Author Subject BorrowerID Book Number Loan Date Date Due Back