2. Our world depends on databases
Google basically IS a database (index)
Facebook is build around databases
So is e-Bay & Netflix and X-Box Live
Travel agents, schools, doctors and hospitals all rely on them
You get the idea!

3. Databases are so useful because they’re so good at storing info
But they do it in a very structured way
That’s so the data can also be sorted
And so the data can also be searched
So overall, what makes databases so special is how they store, sort & search
Let’s look at some examples…

4. Store
Search
Sort

5. We’re actually going to look at databases into two stages.

6. Database Tables Types of Data Relational Databases
First, we’ll learn the basics of how databases work: A
Database Tables B
Types of Data C
Relational Databases

7. A
Database Tables
So we’ve said what makes databases so special is how they store, sort & search
But how can they do that?
The secret is that they work in a very structured or organised way
This starts with the way that all data is stored in what are called tables…

8. Database Tables A Here’s a database table for members of a club...
Field name
Record
Field

9. Database Tables A Here’s a database table for members of a club...
Field name
Record
Field

10. Database Tables A Here’s a database table for members of a club...
Field name
Record
Primary Key
Field

11. Database Tables Recap A Databases store info in a structured way
Data in a database is stored in a table
Each row is called a record
Each column is called a field
A special field called the primary key holds a unique identifier for each record

12. ‘Unique identifiers’ are everywhere!

13. Database Tables Recap A Table Field name Recordl Primary Key Field
All this data is stored in a ??
Table
This is a ??
Field name
This is a ??
Recordl
This is the ??
This is a ??
Primary Key
Field

14. Database Tables Recap A This table has ____ records 4
There are ____ fields 4
The primary key is called _______
LessonID

15. A
Database Tables B
Types of Data C
Relational Databases

16. B
Types of Data
A second secret to how databases work is the way they handle different types of data
Let’s look at an example…

17. Types of Data B Can you spot the different types of data?
We call these ‘data types’
Text
Numbers
Dates

18. B
Types of Data
Database tables can store different data types, such as...
Text
Numbers
Dates
When building a database, you say what type of data can go in each field
This can help prevent errors, such as checking that dates are DD/MM/YY

19. A
Database Tables B
Types of Data C
Relational Databases

20. Relational Databases C
Simple databases with just one data table are called flat file databases.
But using only one table creates BIG problems for larger systems because lots of data can be duplicated and the database becomes very inefficient.
So advanced databases use multiple tables
They are called relational databases
Let’s look at why they are needed…

21. Relational Databases C Notice that several patients see Dr Brown
So her details are duplicated.
This is called redundant data because copies are inefficient & cause inconsistencies
Can you spot one?

22. Relational Databases C PatientID DocID Primary Key Foreign Key DocID

23. Relational Databases We show this relationship in a diagramC
Relational Databases
We show this relationship in a diagram
Doctors
DocID
Surname
Department
Mobile
Patients
Patient ID
Forename
Surname
DocID
It’s a ‘One To Many’ relationship
One doctor can treat many patients

24. Relational Databases C Car Club Again, data is duplicated or redundant
Redundant data causes inconsistencies
Can you spot one?

25. Relational Databases C Car Club SupplierID SupplierID 1 2 3 1 1 2 1 2

26. Relational Databases We show this relationship in a diagramC
Relational Databases
We show this relationship in a diagram
Supplier
SupplierID
CarSupplier
Address1
Town
Postcode
Member
MemberID
Forename
Surname
Car Reg
Car Supplier
It’s a ‘One To Many’ relationship
One Car Supplier can supply many members

27. Relational Databases C Dog Kennel Business
Again, data is duplicated or redundant
Redundant data causes inconsistencies
Can you spot any?

28. Relational Databases C Dog Kennel Business VetID VetID 3 1 2 2 3 2 1
Betta Vetz 2
Top Vets 3
West Vets

29. Relational Databases We show this relationship in a diagramC
Relational Databases
We show this relationship in a diagram
Vet
VetID
VetName
Address1
Town
Postcode
Pets
PetID
Name
Owner Name
Owner Mobile
Vet ID
It’s a ‘One To Many’ relationship
One Car Supplier can supply many members