1. Normalization and Databases
Asfia Rahman

2. What is? process of structuring data within a database.
The process starts with a flat file and finishes with a set of related tables.
UNF / 0NF
1NF
2NF
3NF

3. 0NF Unnormalised form a flat file.
contain non-atomic data, repeating groups of data and possibly redundant data.
Non-atomic data is where a field contains more than one item of data.
Repeating groups of data is when fields are repeated for each record or a record appears to have more than one set of data for a group of fields.
Redundant data exists when data is repeated unnecessarily. This can be spotted when data can be identified by knowing it is dependent upon another field.

4. Examples of redundant data and non-atomic data

5. Examples of repeating and more than 1 set of data (also non-atomic)

6. 1 NF all fields must contain atomic data (1 item only)
there must be no repeating groups of data
there must be a unique key.

7. Changing 0nf to 1nf Non-atomic Data (one field has more than 1 item)
Order ID
Order Date
Customer ID
Customer Name
Customer Address
Product Code
Product name
Quantity
Price
3847
12/9/16
1224
Baker Jones
Somewhere, city
1212
1232
Marzipan
Flour 1 2
$1.50
$0.75
2320
15/10/16
2342
Emma W
Someplace,, cityW
2343
Sugar
Eggs 3 6
$0.83
$0.15
Non-atomic Data (one field has more than 1 item)
Redundant data ( price is repeated every time the product comes)

8. How to do it? Split any repeating group of data into a separate table
Add the key of the original table to act as a foreign key.
Order ID
Order Date
Customer ID
Customer Name
Customer Address
Product Code
Product name
Quantity
Price
3847
12/9/16
1224
Baker Jones
Somewhere, city
1212
1232
Marzipan
Flour 1 2
$1.50
$0.75
2320
15/10/16
2342
Emma W
Someplace,, cityW
2343
Sugar
Eggs 3 6
$0.83
$0.15
Compound key
Order ID
Product Code
Product name
Quantity
Price
3847
1212
Marzipan 1
$1.50
1232
Flour 2
$0.75
2320 3
2342
Sugar
$0.83
2343
Eggs 6
$0.15
Order ID
Order Date
Customer ID
Customer Name
Customer Address
3847
12/9/16
1224
Baker Jones
Somewhere, city
2320
15/10/16
2342
Emma W
Someplace,, cityW

9. 2 NF No partial key dependencies
Means no non-key fields can be dependent upon part of a primary key.
only applies to tables with compound Keys
These fields and that part of the compound key will form a new table.

10. 1nf to 2nf 1
Product Code
Product name
Price
1212
Marzipan
$1.50
1232
Flour
$0.75
2342
Sugar
$0.83
2343
Eggs
$0.15
Order ID
Product Code
Product name
Quantity
Price
3847
1212
Marzipan 1
$1.50
1232
Flour 2
$0.75
2320 3
2342
Sugar
$0.83
2343
Eggs 6
$0.15 2
Order ID
Product Code
Quantity
3847
1212 1
1232 2
2320 3
2342
2343 6
Split out data dependent on only part of a composite key
Add the key of the original table to act as a foreign key.
The PK for the table made will have a CK made up from the original PK along with the main identifier for that group.

11. 3NF no non-key dependencies.
No fields that are dependent upon another field that is not a primary key

12. 2nf to 3nf Split out data dependent on a non-key field
Foreign key will be the non-key field left behind.
Order ID
Order Date
Customer ID
3847
12/9/16
1224
2320
15/10/16
2342
Order ID
Order Date
Customer ID
Customer Name
Customer Address
3847
12/9/16
1224
Baker Jones
Somewhere, city
2320
15/10/16
2342
Emma W
Someplace,, cityW 2 1
Customer ID
Customer Name
Customer Address
1224
Baker Jones
Somewhere, city
2342
Emma W
Someplace,, cityW

13. Final Tables Product Code Product name Price 1212 Marzipan $1.50 1232
Flour
$0.75
2342
Sugar
$0.83
2343
Eggs
$0.15
Order ID
Product Code
Quantity
3847
1212 1
1232 2
2320 3
2342
2343 6
Customer ID
Customer Name
Customer Address
1224
Baker Jones
Somewhere, city
2342
Emma W
Someplace,, cityW
Order ID
Order Date
Customer ID
3847
12/9/16
1224
2320
15/10/16
2342