Tables are normalized to eliminate redundant information, to make updates easier, and to save storage space.
There are three different normalization levels, or forms.
The following slideshow describes the three normal forms.
- second, and .
- third normal forms
1) There are 3 different values stored in a single column, the table is not considered normalized.
2) In the first normal form, information items have been put into their own columns
3) The second normal form introduces a unique value that describes each row, and only that row. Typically the unique identifier has nothing to do with the data in the table, it is usually a counter.
4) In third normal form, the information within each table is not duplicated, and the tables are tied together by the Item name.
An entity is in First Normal Form (1NF) when all tables are two-dimensional with no repeating groups. A row is in first normal form (1NF) if all underlying domains contain atomic values only. 1NF eliminates repeating groups by putting each into a separate table and connecting them with a one-to-many relationship.
First Step to achieve Normalization
Make a separate table for each set of related attributes and uniquely identify each record with a primary key.
- Eliminate duplicative columns from the same table.
- Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key).