Database Normalization:
The main goal of Database Normalization is to restructure the logical data model of a database to:
* Eliminate redundancy
* Organize data efficiently
* Reduce the potential for data anomalies.
Data Anomalies:
Data anomalies are inconsistencies in the data stored in a database as a result of an operation such as update, insertion, and/or deletion.Such inconsistencies may arise when have a particular record stored in multiple locations and not all of the copies are updated.
We can prevent such anomalies by implementing 7 different level of normalization called Normal Forms (NF), first 3 of them are mostly used.
1st Normal Form:
The requirements to satisfy the 1st NF:
* Each table has a primary key: minimal set of attributes which can uniquely identify a record.
* The values in each column of a table are atomic (No multi-value attributes allowed).
* There are no repeating groups: two columns do not store similar information in the same table.
2nd Normal Form:
The requirements to satisfy the 2nd NF:
* All requirements for 1st NF must be met.
* Redundant data across multiple rows of a table must be moved to a separate table.
* The resulting tables must be related to each other by use of foreign key.
3rd Normal Form:
The requirements to satisfy the 3rd NF:
* All requirements for 2nd NF must be met.
* Eliminate fields that do not depend on the primary key;
* That is, any field that is dependent not only on the primary key but also on another field must be moved to another table.
2 comments:
Its quiet a nice & handy post which provides a brief snippet of the database normalization concept. But you havent included 2 other normal forms I guess
not 2 actually, there are more 4 normal forms, that I haven't mentioned as they aren't mandatory for initial concepts..
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