- Normalization is the process of oragnizing data in database effetively.
- In a database normalization is the process of breaking data down into most basic components.
- We can use this to remove redundancy in data.
- Database refinement process that organizes a database; so the data in the database are alwas unambiguous.
Main goal of normalization :
- to reduces the dublicate entries in the database.
- Duplicate entries will occupy more memory space and it leads corruption because same information is stored in different location .
Normalization is the process to avoid this problem, in normalization a set of guideline to be followed to avoid this problem.
- In 1970 ,Edge Codd proposed the first normal form which is represented as 1NF and then he defined normal form two and three.since then several other noramlform have been defined 4NF,5NF and some other normalform are also defined.
First normal form (1NF):
- first normal form sets the very basic rule for an oranised database.
- Elliminate duplicate columns from the same table.
- Create seperate table for each group of releted data and identify each row with a unique column or set of columns(primary key).
Second normal form (2NF):
- second noramal form further address the concept of removing duplicative data.
- The table should meet all the requirements of the first normal form and it removes subset of data that apply to multiple rows of the table and place them in separate table.
- Relationship between these new table are created and their relationship are created the use of foregin keys.
Third normal form (3NF):
- third noramal form (3NF) goes one large step further over other two normal forms.
- The database must meet all the requirements of the seconds form and it removes columns that are not dependent upon the primary key.
Fouth normal form (4NF):
- fourth normal form(4NF) has one additional requirement over the other normal forms.
- The database in this normal form should meet all the requirements of other three normal forms and forms and a relation is in 4NF if it has no multi-value dependencies.
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