Definition of Normalization :
Database Normalization is a technique of organising data in the database.Normalization is a systematic approach of decomposing tables to element data redundancy and undesirable characteristics like insertion, updation,and deletion anomalies.
Why Normalization is required ??
The main objectives of Normalization are :-
# To eliminate redundant data.
# To free the collection of relations from insertion,updation and deletion anomalies.
# To make the relation model more informative to the users.
Redundant data anomaly :-
The database to be designed may suffer from duplication of data.To fulfill the capability of relational database ,it may be required to repeat the values of the data in the database. This resulted in Redundant data anomaly.
Example:
Insertion anomaly :-
The problem of inserting a new tuple into the database without the value of the all attributes Is called insertion anomaly.If new attribute values are to be added to the database,then it can only be done when the values of other attributes of the tuple are available.
Example:
-Here in relation T1 we cannot insert the subject code of mathematics MTMH unless at least one student enroll for that subject.
Deletion anomaly :-
The problem of losing important data of the database by deleting a tuple from the database is called Deletion anomaly.If an tuple is to be deleted,a complete row from the relation is deleted resulting in loss of important data.
For Example :
Consider a relation T1 is consist of the details of a college students.Suppose there is a single student in geography department who withdrawas his enrollment hence his full record or tuple must be deleted.
Along with it we also lose the Information that the subject code of Geography is GEOH.
Updation anomaly :-
When duplicate data is reflected in many rows ,any changes to one attribute value ,then it must replaced in all the other touple otherwise the database will lose it's integrity resulting in updation anomaly.
For Example :
Consider the same relation T1,if it is decided to change the subject code of computer science form CMSH to CMS Then this must be changed thoughtout the database otherwise it may be lead to updation anomaly.
Database Normalization is a technique of organising data in the database.Normalization is a systematic approach of decomposing tables to element data redundancy and undesirable characteristics like insertion, updation,and deletion anomalies.
Why Normalization is required ??
The main objectives of Normalization are :-
# To eliminate redundant data.
# To free the collection of relations from insertion,updation and deletion anomalies.
# To make the relation model more informative to the users.
Redundant data anomaly :-
The database to be designed may suffer from duplication of data.To fulfill the capability of relational database ,it may be required to repeat the values of the data in the database. This resulted in Redundant data anomaly.
Example:
Insertion anomaly :-
The problem of inserting a new tuple into the database without the value of the all attributes Is called insertion anomaly.If new attribute values are to be added to the database,then it can only be done when the values of other attributes of the tuple are available.
Example:
Deletion anomaly :-
The problem of losing important data of the database by deleting a tuple from the database is called Deletion anomaly.If an tuple is to be deleted,a complete row from the relation is deleted resulting in loss of important data.
For Example :
Consider a relation T1 is consist of the details of a college students.Suppose there is a single student in geography department who withdrawas his enrollment hence his full record or tuple must be deleted.
Along with it we also lose the Information that the subject code of Geography is GEOH.
Updation anomaly :-
When duplicate data is reflected in many rows ,any changes to one attribute value ,then it must replaced in all the other touple otherwise the database will lose it's integrity resulting in updation anomaly.
For Example :
Consider the same relation T1,if it is decided to change the subject code of computer science form CMSH to CMS Then this must be changed thoughtout the database otherwise it may be lead to updation anomaly.
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