Example Normalisation

Un-Normalised Data

Data is presented in a single column. In tis caste the following data is contained:
Quantity, Item ID and item Description. Since multiple unrelated values are stored in a column, this data is considered un-normalised.

First normal Form

Data is now in First Normal Form (1NF). Data items have been put in their own columns, and the columns furnished with a description. For data to be in 1NF each piece of information should be in its own column,and each row of data should contain the same columns.

Second Normal Form

Data is now in Second Normal Form (2NF). 2NF is based on 1NF, with the addition that a unique identifier is added to each row - In this case the OrderID value. In most cases this unique value is a counter, rather than being related to the data. Each non-key attribute should be functionally dependent on the primary key for the table.

Third Normal Form

Data is now in Third Normal Form (3NF). All attributes not dependent on the primary key should be moved to a separate table. Repetition of data is also eliminated. In this case, the tables are linked by the ItemCode attribute.