Normalization || Database Management System || BcisNotes

Normalization

Normalization presents a set of rules that tables and databases must follow to be well structured. Database Normalization is a technique of organizing the data in the database. Normalization is a systematic approach of decomposing tables to eliminate data redundancy(repetition) and undesirable characteristics like Insertion, Update, and Deletion Anomalies. It is a multi-step process that puts data into tabular form, removing duplicated data from the relation tables.

Normalization is used for mainly two purposes,

• Eliminating redundant(useless) data.
• Ensuring data dependencies make sense i.e data is logically stored.

There are three types of normalization.

1. First normalization form rules
2. Second normalization form rules
3. Third normalization form rules

(1NF)Rules

• Each table cell should contain a single value.
• Each record needs to be unique.
• Values stored in a column should be of the same domain
• And the order in which data is stored does not matter.

(2NF)Rules

• Rule 1- Be in 1NF
• Rule 2- Single Column Primary Key
• should not have Partial Dependency.

It is clear that we can’t move forward to make our simple database in the 2nd Normalization form unless we partition the table above.

Membership ID	Full Name	Physical Address	Salutation
1	Janet Jones	First street plot 34	Ms.
2	Robert Phil	3rd street 34	Mr.
3	Robert Phil	5th Avenue	Mr.

 

Membership ID	Movies Rented
1	Pirates of the Caribbean
1	Clash of the titans
2	Forgetting Sarah marshal
2	Daddy,s little girls
3	Clash of the titans

(3NF)

• Rule 1- Be in 2NF
• Rule 2- Has no transitive functional dependencies

To move our 2NF table into 3NF, we again need to again divide our table.

MEMBERSHIP ID	FULL NAMES	PHYSICAL ADDRESS	SALUTATION ID
1	Janet Jones	First street plot No	2
2	Robert Phil	3rd Street 34	1
3	Robert Phil	5th Avenue	1

MEMBERSHIP ID	MOVIES RENTED
1	Pirates of the Caribbean
1	Clash of the Titans
2	Forgetting Sarah Marshal
2	Daddy’s Little girls
3	Clash of the Titans

SALUTATION ID	SALUTATION
1	Mr.
2	Ms.
3	Mrs.
4	Dr.

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