REGARDING NORMALIZATION IN DATABASE

Posted by Bca1023 under Sql Server on 9/2/2012 | Points: 10 | Views : 1177 | Status : [Member] | Replies : 2
IF ANYONE HAVING THE IDEA ABOUT BCNF,4NF,5NF,6NF,EKNF,DKNF OF NORMALIZATION RELATED TO DATABASE?

IF YES, THEN TELL ME BRIEFLY ABOUT THEM WITH EXAMPLE.





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Posted by: Ranjeet_8 on: 9/3/2012 [Member] [MVP] Gold | Points: 25

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Normalization is the process of simplifying the relationship between data elements in a record.
(i) 1st normal form: - 1st N.F is achieved when all repeating groups are removed, and P.K should be defined. big table is broken into many small tables, such that each table has a primary key.
(ii) 2nd normal form: - Eliminate any non-full dependence of data item on record keys. I.e. The columns in a table which is not completely dependent on the primary key are taken to a separate table.
(iii) 3rd normal form: - Eliminate any transitive dependence of data items on P.K's. i.e. Removes Transitive dependency. Ie If A is the primary key in a table. B & C are columns in the same table. Suppose C depends only on B and B depends on A. Then C does not depend directly on primary key. So remove C from the table to a look up table.

Look at this url for more details :
http://www.aliencoders.com/content/basics-normalization-examples




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Posted by: Muhsinathk on: 9/3/2012 [Member] Bronze | Points: 25

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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
1 NF
1. There are no duplicated rows in the table.
2. Each cell is single-valued (i.e., there are no repeating groups or arrays).
3. Entries in a column (attribute, field) are of the same kind.

2 NF
A table is in 2NF if it is in 1NF and if all non-key attributes are dependent on the entire key.

3 NF

A table is in 3NF if it is in 2NF and if it has no transitive dependencies

BCNF

A relation is in Boyce-Codd Normal Form (BCNF) if every determinant is a candidate key
4 NF

A relation is in 4NF if it has no multi-valued dependencies.


DKNF

A key uniquely identifies each row in a table. A domain is the set of permissible values for an attribute. By enforcing key and domain restrictions, the database is assured of being freed from modification anomalies. DKNF is the normalization level that most designers aim to achieve.

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