Database normalization (NF)

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What is Database Normalization? Explain 3NF ?

  1. Post:140

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    Re: Database normalization (NF)

    Database Normalization is a technique of organizing the data in the database. Normalize the redundancy with Insertion, Update and Deletion Anamolies of the data into database. It is a multi- step process in which we gave data in tubler form and than removing duplicated data from the relation tables. 

    Third normal form(3NF) is used in database normalization as a normal form.its states in that table is in 3NF. The given relation R(table)is in 2NF. Every non-prime attribute is non-transitively dependent on every key in R. 

    Example : 

    CREATE TABLE CUSTOMERS( 
       CUST_ID INT NOT NULL,
       CUST_NAME VARCHAR (20) NOT NULL,
       DOB DATE,
       STREET VARCHAR(200),
       CITY VARCHAR(100),
       STATE VARCHAR(100),
       ZIP VARCHAR(12),
       EMAIL_ID VARCHAR(256),
       PRIMARY KEY (CUST_ID)
    );

    in transitive dependency with the third normal form, all you need to do is to move the Street, City and the State fields into their own table. 

    CREATE TABLE ADDRESS( 
       ZIP VARCHAR(12),
       STREET VARCHAR(200),
       CITY VARCHAR(100),
       STATE VARCHAR(100),
       PRIMARY KEY (ZIP)
    );

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