Normalization
, Definition
• Database normalization is the process of organizing
the fields and tables of a relational database to
minimize redundancy and dependency.
• 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 via the defined relationships.
, What is anomalies ?
Database anomalies are the problems in relations that
occur due to redundancy in the relations.
These anomalies affect the process of inserting,
deleting and modifying data in the relations. Some
important data may be lost if a Relation is updated that
contains database anomalies.
It is important to remove these anomalies in order to
perform different processing on the relations without
any problem.
, Types of Anomalies.
• Redundancy
– Repeat info unnecessarily in several tuples
• Update anomalies:
– Change info in one tuple but not in another.
• Deletion anomalies:
– Delete some values & lose other values too.
• Insert anomalies:
– Inserting row means having to insert other, separate info.
, Definition
• Database normalization is the process of organizing
the fields and tables of a relational database to
minimize redundancy and dependency.
• 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 via the defined relationships.
, What is anomalies ?
Database anomalies are the problems in relations that
occur due to redundancy in the relations.
These anomalies affect the process of inserting,
deleting and modifying data in the relations. Some
important data may be lost if a Relation is updated that
contains database anomalies.
It is important to remove these anomalies in order to
perform different processing on the relations without
any problem.
, Types of Anomalies.
• Redundancy
– Repeat info unnecessarily in several tuples
• Update anomalies:
– Change info in one tuple but not in another.
• Deletion anomalies:
– Delete some values & lose other values too.
• Insert anomalies:
– Inserting row means having to insert other, separate info.
