1. Databases
A brief introduction…

2. Definition
A collection of non-redundant data shareable between different application (software).

3. Types
There are two types of databases:
Flat file
Relational

4. Flat-File
This is a single table database with separate copies of data in each part of the business.
An example could be a phonebook.

5. Problems with flat-file
Data duplication
Wastes disk space and slows down query time.
Maintenance
Every instance of a piece of data needs to be updated if changed.
Error
More reliance on manual data entry means that data is more likely to contain errors.

6. Relational A collection of related files organised.
Data is divided into logical groups and stored in multiple tables. The tables are then connected to each other through relation.

7. Characteristics Data is stored in a set of tables
Tables are joined using relational links
Reduces duplication of data in database
Data is normalised
Allows for greater flexibility and efficiency

8. Relationships
Each table must have a unique reference for each record – primary key
A composite primary key is where the p.k consists of several data items
Linking a p.k to other tables creates the foreign key
Foreign key are the relationships which links the tables together