1. Normalisation FORM RULES 1NF 2NF 3NF

2. What is normalisation of data? The process of Normalisation organises your database to: Reduce or minimise redundant data. Promote Data Integrity. Ensure that related data are stored in a given table.

3. Rules called ‘Normal Forms’ have been developed to allow a database to be designed with different levels of efficiency. They are : Unnormalised Form0NF First Normal Form1NF Second Normal Form2NF Third Normal Form3NF Fourth Normal Form4NF Fifth Normal Form5NF

4. 1NF – First Normal Form Break each field down to the smallest meaningful value

5. 2NF – Second Normal Form 2NF attempts to reduce the amount of redundant data in a table by extracting it, placing it in new table(s) and creating relationships between those tables.

6. 3NF – Third Normal Form Remove fields that do not relate to, or provide a fact about, the primary key

7. Student #First NameSurnameTelephone 1Telephone 2 1456987PeterAdam03 945978940401569784 Student #First NameSurnameFull Name 1456987PeterAdamPeter Adam 1NF (First Normal Form) 1)No column with repeated of similar data. Examples of repeated or similar data:

8. 2) Each data item cannot be broken down any further or must be ‘atomic’ data, without losing its meaning. Example of data that cannot be broken down further or ‘atomic’ data: An ID number (student id number, licence number) Stock Code Number PN10081 A telephone number A First Name or Surname A Description (This computer is broken)

9. Examples of data that can still be broken down or is NOT ‘atomic’: A full name: “Christopher Jones” Can be broken down to: A complete address: 62 Southern Rd, West Heidelberg, VIC, 3081 Can be broken down to… ?: Student #First NameSurname 1456987ChristopherJones Student #Full Name 1456987Christopher Jones Student #First NameSurnameAddress 1456987ChristopherJones62 Southern Rd, West Heidelberg, VIC, 3081

10. 1)Each row is unique (no duplicate records). 2) Each Field has a unique name.

11.  Repeated or Redundant Fields?  Data Atomic?  Primary Key?  Each Field Name Unique?  Each row (record) Unique? 1NF?

12. 2NF (Second Normal Form) 1) Must be in 1NF already 2) Non-key attributes must depend on the (so no redundant data is being stored) TIP: Attribute = Field of data Attribute = Field of data

13. Example: This is not in 2NF: What data is redundant? Or repeated? What data is not dependant on Course (key- attribute)? Course #Semester Amount of Student Places Available Course Name IT0012012 -150Multimedia IT0012012 -250Multimedia IT0022012 -1100Programming IT0022012 -2100Programming IT0032012 -180Databases IT0032012 -280Databases IT0042012 -1100OO Programming

14. If we create a new Table called Course #, such as below: We have now eliminated the redundancy of data. Course #Course Name IT001Multimedia IT002Programming IT003Databases IT004OO Programming

15. Example: Here we have a lot of repetitive data. And City and State rely on Post Code, not necessarily the key-attribute (Customer #). Customer #First NameSurnameCityState Post Code 789LucyJonesMelbourneVIC3081 790EmmaMooreMelbourneVIC3081 791PeterSmithGeelongVIC3052 792KurtDavisGeelongVIC3052 CityState Post Code MelbourneVIC3081 MelbourneVIC3122 GeelongVIC3052 GeelongVIC3052

16. Post CodeCityState 3081MelbourneVIC If we create a new table called Post Codes Post CodeCityState 3081MelbourneVIC 3052GeelongVIC Customer #First NameSurnamePost Code 789LucyJones3081 +

17.  1NF?  Dependant on Key-attributes?  No repeated data? 2NF?

18. 3NF (Third Normal Form) 1) Must be in 2NF 2) There are no non-key attributes that depend on another non-key attribute. In other words: Data in your table must depend on the primary key only.

19. Remove fields that do not relate to, or provide a fact about, the primary key In this case Supplier Phone does not relate to the Primary Key (Product #) but relates to Supplier. Product #DescriptionCostSupplier Name Supplier Phone 00221Ring$5RingsRUs0482987623

20. So in creating a new Table, Supplier: We are eliminating redundancy of information in our Product table, which will now look like this: And have a relationship with: Supplier #Supplier Name Supplier Phone 1RingsRUs0482987623 Product #DescriptionCostSupplier # 00221Ring$51 Supplier #Supplier Phone 10482987623

21.  2NF?  All fields rely on only the Primary key? 3NF?