Normalizing Techniques - A closer look
More often than not database users have not able to
understand what the various normalization techniques are. In this article
I would try to address these principles in a simple terms and examples.
Applying and knowing the principles of normalize and implement the them to your
daily database design is an simple process and this can come with performance
improvements. Not wasting much time lets get going ...
What is Normalization?
Normalization is a process of efficiently organizing
your data in your database. The goals in doing so: Eliminate all the
redundant data and ensure data dependencies. Both of these goals are worth
achieving. Normalizing tables would reduce the amount of space a database may
And as said earlier each of these are a set of rules.
Each of these rules are called as "Normal Form" or NF in short. All the rules
are cummulative in nature. Meaning if we have three of the rules adhered then
we are in the 3NF. In this document we will
First Normal Form ( 1NF )
Eliminate repeating groups from the same table
Aggregate similiar data in separate tables and
identify each row with an unique identifier
In simple language if we were to say each attribute of
the relation would be atomic in nature for 1NF. Look at the example below to
Second Normal Form ( 2NF )
Moving forward lets take a look at the rules that
goven 2NF. We get a step even more closer to remove duplicate records.
Remove data that apply to multiple rows and place
them in a separate table
Relate the above table with foreign keys
Consider the below example to understand the same.
Third Normal Form ( 3NF )
This is the most preferred normalization technique
followed for most of the database.
Values in a record that are not part of that record's
key do not belong in the table. In general, any time the contents of a group of
fields may apply to more than a single record in the table, consider placing
those fields in a separate table.
Note: All these normalization are
cummulative in nature. I re-iterate this point.
There are 4NF otherwise called as Boyce-Codd normal
form (BCNF). I wouldnot deal much into this form as it becomes far beyond
practicle limits to have such a requirement. The rule is, we are in BCNF if and
only if every determinant is a candidate key.