Database Design is very essential for all Softwares. We Know that database is used to store data.

Database is known as collection of tables. Table is collections  of fields.

Primary key is used in tables to make the field unique and avoid repetation. The table should have only one primary key.

To design the database we are using Normalization. Normalization is used to remove repetations and increases the clarity in organizing data in a database.

There are 5 rules in normalization. They are

  • 1st Normal Form -  Each column type should be unique to eliminate duplication.

  • 2nd Normal Form -  Use 1st normal form and then remove subsets of data that apply to multiple rows of a table and place them in separate tables. Create relationship between tables.

  • 3rd Normal Form - Use 2nd normal form and then delete column that are not dependent on primary key

  • 4th Normal Form - Use 3rd normal form and check it has multi-value dependencies.

  • 5th Normal Form - Use 4th normal form and  check it should not have cyclic dependencies in a composite key

For more details and information we see the following site

http://en.wikipedia.org/wiki/Database_normalization

http://databases.about.com/od/specificproducts/a/normalization.htm

http://www.devshed.com/c/a/MySQL/An-Introduction-to-Database-Normalization/


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