Chapter 18 - Databases

Create a database structure

What is a database?

• A database is an organised collection of data which stores and retrieves data.

• Flat-file databases

• Relational databases

Field

• Single item of data

• Each field has a field name 

• Each field contains one type of data

Record

• A collection of fields

File

• Organised collection of records

• Can have one or more tables within

Flat-file databases

• Data is stored in one table

• Organised by rows and columns

Relational databases

• Data is stored in more than one linked table, stored in a file

• Tables within relational databases are linked with relationships

Key fields

• The relationships linking the tables

Primary and foreign key fields

• Primary key field that holds unique data and is the field used to identify that record

• Foreign key fields store values from a primary key field in another table

Data types and sub-types

• Alphanumeric

- text

• Numeric

- integer

- decimal

- currency

• Boolean

- Yes/No

- True/False