Data base normalization

Database normalization is the process of organizing the fields and tables of a relational database to minimize redundancy. Normalization usually involves dividing large tables into smaller (and less redundant) tables and defining relationships between them. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database using the defined relationships.

 Normalization is the process of efficiently organizing data in a database. There are two goals of the normalization process: eliminating redundant data (for example, storing the same data in more than onetable ) and ensuring data dependenciesmake sense (only storing related data in a table). Both of these are worthy goals as they reduce the amount of space a database consumes and ensure that data is logically stored.

First Normal Form

  • Eliminate repeating groups in individual tables.
  • Create a separate table for each set of related data.
  • Identify each set of related data with a primary key.

Second Normal Form

  • Create separate tables for sets of values that apply to multiple records.
  • Relate these tables with a foreign key.

Third Normal Form

  • Eliminate fields that do not depend on the key.


Fouth and Fifth normal form is very rear to come into the picture :)


First Normal Form (1NF)

First normal form (1NF) sets the very basic rules for an organized database:
  • 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).

Second Normal Form (2NF)

Second normal form (2NF) further addresses the concept of removing duplicative data :
  • Meet all the requirements of the first normal form.
  • Remove subsets of data that apply to multiple rows of a table and place them in separate tables.
  • Create relationships between these new tables and their predecessors through the use of foreign keys.


Third Normal Form (3NF)

Third normal form (3NF) goes one large step further:
  • Meet all the requirements of the second normal form.
  • Remove columns that are not dependent upon the primary key.

In fourth normal form we can use candidate key :)



















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