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Question: What is Normalization, First Normal Form, Second Normal Form , Third Normal Form
Answer:
Answer posted by Badri Santhosh on 2005-05-18 09:40:29: Normalization : The process of decomposing tables to eliminate data redundancy is called Normalization.
1N.F:- The table should caontain scalar or atomic values.
2 N.F:- Table should be in 1N.F + No partial functional dependencies
3 N.F :-Table should be in 2 N.F + No transitive dependencies |
| July 07, 2005 04:00:42 |
#3 |
| murali |
Member Since: Visitor Total Comments: N/A |
RE: What is Normalization, First Normal Form, Second Normal Form , Third Normal Form
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Normalization can be defined as segregating of table into two different tables, so as to avoid duplication of values.
The normalization is a step by step process of removing redundancies and dependencies of attributes in data structure
The condition of data at completion of each step is described as a “normal form”.
Needs for normalization : improves data base design.
Ensures minimum redundancy of data.
Reduces need to reorganize data when design is modified or enhanced.
Removes anomalies for database activities.
First normal form :
· A table is in first normal form when it contains no repeating groups.
· The repeating column or fields in an un normalized table are removed from the table and put in to tables of their own.
· Such a table becomes dependent on the parent table from which it is derived.
· The key to this table is called concatenated key, with the key of the parent table forming a part it.
Second normal form:
· A table is in second normal form if all its non_key fields fully dependent on the whole key.
· This means that each field in a table ,must depend on the entire key.
· Those that do not depend upon the combination key, are moved to another table on whose key they depend on.
· Structures which do not contain combination keys are automatically in second normal form.
Third normal form:
· A table is said to be in third normal form , if all the non key fields of the table are independent of all other non key fields of the same table.
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