3NF Vs. BCNF in DBMS: Know the
Difference Between 3NF and BCNF
Both of these are parts of the Database Management System (DBMS), but there is a primary difference between 3NF and BCNF in DBMS. In this article, we will discuss the same. But let us first know a bit more about each of these individually.
What is 3NF?
The term 3NF is an acronym for Third Normal Form. We can say that a relation is in Third Normal Form when it’s in 2NF, and none of the non-key attributes transitively depend on the given primary key. It means that no transitive dependency is present there. Along with that, the relation should satisfy one of the conditions given below.
For a function dependency of C->D:
- The D should be the prime attribute. It means that the D must be the candidate key’s part.
- The C should be a super key.
We use 3NF for reducing duplication of data and for attaining data integrity.
What is BCNF?
The term BCNF is an acronym for Boyce-Codd NF (normal form). E.F Codd and R.F Boyce made BCNF in 1974. We can say that a functional dependency is in BCNF only if it holds these properties:
- In the case of a functional dependency P>Q, P must be a super key.
- It must already exist in 3NF.
The BCNF acts as an extension to 3NF. It consists of more strict rules as compared to the 3NF. And also, it is comparatively much stronger as compared to 3NF.
Difference Between 3NF and BCNF in DBMS
Here are the differences between 3NF and BCNF in DBMS:
| Parameters | 3NF | BCNF |
| Strength | 3NF is comparatively less strong than that of the BCNF. | BCNF is comparatively much stronger than that of the 3NF. |
| Functional Dependencies | The functional dependencies in 3NF already exist in 2NF and INF. | The functional dependencies in BCNF already exist in 3NF, 2NF, and INF. |
| Redundancy | 3NF has a comparatively much higher redundancy. | BCNF has a comparatively much lower redundancy. |
| Functional Dependencies | In the case of 3NF, preservation occurs for all the functional dependencies. | In the case of BCNF, there is no preservation for all the functional dependencies. |
| Lossless Decomposition | Lossless decomposition is comparatively much easier to achieve in the case of 3NF. | Lossless decomposition is comparatively much harder to achieve in the case of BCNF. |
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