1. Learning Objectives
understand the characteristics of structured and unstructured data
understand that data can be decomposed, organised and managed in a structured database (tables, records, fields, relationships, keys)

2. Why are databases so important?
Definition
“A database is a computerised system that makes it easy to search, select and store information.”

3. Databases are used everywhere…
Snap Inc, parent company of Snapchat, collect a huge amount of data from YOU, all stored in their databases:
Your details (whatever you chose to provide when signing up)
Opened snaps/photos you have taken (for 30 days)
Unopened group snaps (for 24 hours)
Device location
Device type (iPhone, Samsung Galaxy etc)
What filters you are using
User created content such as stickers
How many times you log in
AND MUCH MUCH MORE!
This would not be possible without a database to store this data in, and the functionality to be able to search and update it.

4. Even when you are chilling out….
The PSN uses a database to store:
Your personal information (name, address etc)
Your payment information (credit card / debit card)
Your purchase history/games library
Your friends/contact list
Subscription type

5. You just can’t escape them
The NHS uses a databases to store:
Patient details (address, medical history)
Employee details (consultants, nurses, admin, cleaners etc!)
Hospital beds available
Drugs/Medicines issued to patients
Without a computerised system, what could happen for a patient taken to A&E for an emergency?
What could happen if the database is not up to date?
The PSN uses a database to store:
Your personal information (name, address etc)
Your payment information (credit card / debit card)
Your purchase history/games library
Your friends/contact list
Subscription type

6. And loads of others…
Our school uses a database to store information about attendance or to store pupils' and teachers' contact information. A database like this will probably be protected with a password to make sure that people’s personal information is kept safe.
A library might also use a database to keep track of which books are available and which are on loan.

7. Structured / Unstructured Data
Data can be stored in either an unstructured or structured way.
Structured data is easier for a computer to interact with, process. This is because data is arranged in a standard, precise layout.
Unstructured data cannot be easily understood by computers and is harder to search, organise and store.

8. Structured vs Unstructured Data

9. How is data stored in databases?
Ok, so we know that databases are used to store different types of data.
But what does this actually look like?
Databases make use of tables to store data.
tbl_users
USER_ID
NAME
PASSWORD
BIRTHDAY
GENDER
103435
Ronald Koeman
Everton4lyf
04/12/1956 M
103436
Sergio Aguero
Kunaguero123
12/01/1989
103437
Miley Cyrus
Imakebadmusic99
10/10/1995 F
103438
Ryan Thomas
IdidntPunchHer2018
03/05/1987
103439
Roxanne Pallett
imsorryIOverReacted
23/07/1979

10. Tables, Fields and Records
Tables are the objects in a database that store data.
Data is stored in records (rows) and columns (fields).
The primary key is the unique identifier for each record.
Fields
USER_ID
NAME
PASSWORD
BIRTHDAY
GENDER
103435
Ronald Koeman
Everton4lyf
04/12/1956 M
103436
Sergio Aguero
Kunaguero123
12/01/1989
103437
Miley Cyrus
Imakebadmusic99
10/10/1995 F
103438
Ryan Thomas
IdidntPunchHer2018
03/05/1987
103439
Roxanne Pallett
imsorryIOverReacted
23/07/1979
Records
Primary Key

11. Activity
You will fill in your first (flat file) database, on paper:

12. Activity We are now going to set this table up in Microsoft Access.
Watch the demonstration.
Screenshot and print – label the primary key, field, record.

13. How is data stored in databases?
So far, we have seen a database with just one table. In reality, a database is made up of multiple tables, that all link together.
This is what is known as a relational database.
A 'flat-file' database is one that only contains a single table of data, but we shouldn’t really like or use them, as they are extremely limited and really quite rubbish!

14. Why is a flat file database “rubbish”?
The main reason is something we call data duplication. This means that the same data appears multiple times, which can significantly add to the storage size of a database, particularly when there are millions of records within it.

15. Relational Database
A 'relational' database is one that contains two or more tables of data, connected by links called relationships. 
In this example the information is split into two different tables- Student and Class.
However you can see where the information in the Student table also appears in the Class table.

16. Data Types Text -Stores letters, numbers and symbols
Number- Used to store numbers, both positive, negative and decimals
Date / Time- Used to store dates and times
Currency- Used to store anything related to prices or money
Yes / No- Gives just two options – yes and no

17. Relationship Types