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Normal Forms

20 October, 2015 - 09:32

All the tables in any database can be in one of the normal forms we will discuss next. Normalization is the process of determining how much redundancy exists in your tables. Idealy we only want minimal redun dancy. That is PK to FK. Everything else should be derived from other tables. There are 6 normal forms, but we will only look at the first 4. The last two are rarely used.

1stNormal Form

2ndNormal Form

3rdNormal Form

BCNF

First Normal Form

In the first normal form only single values are permitted at the intersection of each row and column hence, there are no repeating groups.

To normalize a relation that contains a repeating group, remove the repeating group and form two new relations.

The primary key of the new relation is a combination of the primary key of the original relation plus an attribute from the newly created relation for unique identification.