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
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.
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 |
| STU_ID | Interest |
|---|---|
| 66_3sk | Drums |
| 66_3sk | Ayurveda |
| 73_prash | Drums |
| 79_sanju | Sports |
| 82_srinu | Aerobics |
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