Types of Database (Cambridge (CIE) IGCSE ICT)
Revision Note
Types of databases
What is a database?
A Database is a structured, persistent collection of data
It allows easy storage, retrieval, and management of information
Electronic databases offer a number of key benefits:
Easier to add, delete, modify and update data
Data can be backed up and copied easier
Multiple users, from multiple locations, can access the same database at the same time
There are two main types of database
Flat file
Relational
Flat file database
A flat file database is one that stores all data in a single table
It is simple and easy to understand but causes data redundancy, inefficient storage and is harder to maintain
Consider this example flat file table of students
This table has redundant data - the tutor and form room information repeats, this is inefficient
If a tutor changed their name we would need to find all instances of that name and change them all
Missing any would mean the table had inconsistent data
Relational database
A relational database is one that organises data into multiple tables
It uses keys to connect related data which reduces data redundancy, makes efficient use of storage and is easier to maintain
A relational database solves the issues in a flat file database:
A new table could be created to store the tutor information and the tutor information in the student table could be moved to the new table
Then a foreign key in the student table (TutorID) could link a student to their tutor
Now the name of each tutor and their form room is stored only once
This means if they change only one piece of data, the data is updated in the entire database and inconsistency is avoided
Tables & records
What is a table?
A table is a complete set of records about the same subject/topic in a database
An example of a database table named cars is below
cars
car_id | make | model | colour | price |
---|---|---|---|---|
1 | Peugeot | 2008 | Red | 24950 |
2 | Mazda | MX5 | Blue | 17995 |
3 | Citroen | DS4 | Black | 21450 |
4 | Ford | Puma | White | 19500 |
What is a record?
A record is complete set of fields on a single entity in a table (row)
An example of a record in the cars table below is highlighted in green
cars
car_id | make | model | colour | price |
---|---|---|---|---|
1 | Peugeot | 2008 | Red | 24950 |
2 | Mazda | MX5 | Blue | 17995 |
3 | Citroen | DS4 | Black | 21450 |
4 | Ford | Puma | White | 19500 |
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