4-NF form in DBMS

About 4-NF Form in DBMS

In this article, we will learn about 4-NF Form in DBMS.
Normalization is a process of breaking a table into you still optimized ones so that they are free from all problems faced due to insertion updation and deletion of data in the table

 

4-NF form in DBMS

4-NF form in DBMS

 

In this article, we will learn about the 4-NF form in DBMS.

Normalization is a process of breaking a table into two smaller ones that are free from insertion and deletion and update  problems

4-NF  is the highest level of normalization.

 

4th Normal form in DBMS

Fourth Normal Form

Definition of 4th Normal Form

The table is said to be  in 4th Normal Form it is it satisfies the following properties

    • It should be in Boyce Codd normal form(BCNF)
    • It is free from multivalued dependency.

What is a multivalued dependency

A Dependency A->B for a single value of  A  there exist multiple values of B, then search dependencies are called as a multivalued dependency

Problem table: STUDENT
STU_ID Course Interest
66_3sk Programming Drums
66_3sk Math Ayurveda
73_prash Data Mining Drums
79_sanju WPS Sports
82_srinu Math Aerobics
 
  • Given table is in First Normal Form because there is no multivalued attribute, it is in second normal form and third Normal Form because it is free from all kinds of partial dependency, full dependency  and transitive dependency and it is in BCNF because in  all the dependencies left side  attribute is a super key
  • Here student id 66 appears two times  in courses and interests column and it leads to unnecessary repetition of data.

Procedure to Convert a table to 4-NF

Break the given tables into two different tables ensure that on multiple values are not mapped for a single attribute STUDENT_COURSE
STU_ID COURSE
66_3sk Programming
66_3sk Math
73_prash Data Mining
79_sanju WPS
82_srinu Math
STUDENT_INTEREST
STU_ID Interest
66_3sk Drums
66_3sk Ayurveda
73_prash Drums
79_sanju Sports
82_srinu Aerobics

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