Normalization is the process of efficiently organizing data in a database. There are two goals of the normalization process: eliminating redundant data (for example, storing the same data in more than one table) and ensuring data dependencies make sense (only storing related data in a table). Both of these are worthy goals as they reduce the amount of space a database consumes and ensure that data is logically stored. To make the data insertion and retrieval more faster.
First Normal Form (1NF)
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First normal form (1NF) sets the very basic rules for an organized database:
>> Eliminate duplicative columns from the same table. - no repeating groups
>> Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key). - Contains only atomic values
Eg: Student, Age, Subject
Gaurav , 32, (Computers, Maths) -- 1st NF --> Gaurav , 32, Computers
Gaurav, 32, Maths
Second Normal Form (2NF)
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Second normal form (2NF) further addresses the concept of removing duplicative data:
>> Meet all the requirements of the first normal form.
>> Remove subsets of data that apply to multiple rows of a table and place them in separate tables.
>> Create relationships between these new tables and their predecessors through the use of foreign keys.
Eg: Storing EmpId, EmpName, Emp DoJ, Emp Salary month, Emp Salary Amount.
In this case EmpName will be redundant data. Break it into 2 tables:
Table-1: EmpId, EmpName, Emp DoJ
Table-2: EmpId, EmpSal month, EmpSal Amount
Third Normal Form (3NF)
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Third normal form (3NF) goes one large step further:
>> Meet all the requirements of the second normal form.
>> Remove columns that are not dependent upon the primary key.
Eg1: Tournament, Year, Winner, Winner Date of Birth
2 Tables:
Tournament, Year, Winner
Winner, Winner Date of Birth
Eg2: StudentID, StudentName, Student School Name, School Students count
2 Tables:
StudentID, StudentName, Student School Name,
Student School Name, School Students count
Thumb Rule:
1st NF - Remove redundant columns
2nd NF - Remove redundant rows
3rd NF - Remove columns/data which is not dependent upon PK.
First Normal Form (1NF)
---------------------------------
First normal form (1NF) sets the very basic rules for an organized database:
>> Eliminate duplicative columns from the same table. - no repeating groups
>> Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key). - Contains only atomic values
Eg: Student, Age, Subject
Gaurav , 32, (Computers, Maths) -- 1st NF --> Gaurav , 32, Computers
Gaurav, 32, Maths
Second Normal Form (2NF)
------------------------------------
Second normal form (2NF) further addresses the concept of removing duplicative data:
>> Meet all the requirements of the first normal form.
>> Remove subsets of data that apply to multiple rows of a table and place them in separate tables.
>> Create relationships between these new tables and their predecessors through the use of foreign keys.
Eg: Storing EmpId, EmpName, Emp DoJ, Emp Salary month, Emp Salary Amount.
In this case EmpName will be redundant data. Break it into 2 tables:
Table-1: EmpId, EmpName, Emp DoJ
Table-2: EmpId, EmpSal month, EmpSal Amount
Third Normal Form (3NF)
----------------------------------
Third normal form (3NF) goes one large step further:
>> Meet all the requirements of the second normal form.
>> Remove columns that are not dependent upon the primary key.
Eg1: Tournament, Year, Winner, Winner Date of Birth
2 Tables:
Tournament, Year, Winner
Winner, Winner Date of Birth
Eg2: StudentID, StudentName, Student School Name, School Students count
2 Tables:
StudentID, StudentName, Student School Name,
Student School Name, School Students count
Thumb Rule:
1st NF - Remove redundant columns
2nd NF - Remove redundant rows
3rd NF - Remove columns/data which is not dependent upon PK.
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