its nothing like that!
1NF - every record in the table has to be same length. This means that each record has the same number of fields, and none of them contains a blank box (wastes space) or more than one value (on a computer database, if you put two values for one field, you have to create an entire new row (lots of blank boxes) -> waste space).
_________
2NF - 1NF and in addition, all fields are dependent on the whole of the primary key (i think this means what i'm showing below)
_________
Employee Table
Employee ID
Employee Name
Employee Ph No.
---
Shifts Table
Employee ID
Shift Times
If we know the employee id, we should know their name and phone number...
If we know their id, we know their shift times...
_________
3NF - 1NF, 2NF and in addition, all fields (attributes) should be dependent on the tables primary key. If they are not they should be put in their own table. This means that every attribute unless it is a primary or foreign key must be DIRECTLY dependent on the Primary Key of this table and not on some other column.
Someone correct me if i'm wrong...
A good way to understand 2NF and (maybe) 3NF, is thinking "if i know". If you know something about a customer/employee/person, what else do you know?
zer.0.ne said:
I don't think we need to know 1NF 2NF and 3NF specifically.. it has never been asked.
From the syllabus:
data modelling tools for organising data including:
- blah
- blah
-
Normalising data to reduce data redundancy.
THe syllabus is brief on that point, that statement COULD imply knowledge of 1NF, 2NF, 3NF normalisation.
