## How BCNF is stronger than 3NF in database decomposition?

BCNF is a stronger form of normalization than 3NF because it eliminates the second condition for 3NF, which allowed the right side of the FD to be a prime attribute. Thus, every left side of an FD in a table must be a superkey. Every table that is BCNF is also 3NF, 2NF, and 1NF, by the previous definitions.

**Is BCNF or 3NF better?**

This relation is in BCNF as it is already in 3Nf (there is no prime attribute deriving no prime attribute) and on the left hand side of the functional dependency there is a candidate key….Difference between 3NF and BCNF :

S.NO. | 3NF | BCNF |
---|---|---|

2. | It is less stronger than BCNF. | It is comparatively more stronger than 3NF. |

**What BCNF is stronger than 3NF?**

Answer: BCNF is a stronger form of normalization than 3NF because it eliminates the second condition for 3NF, which allowed the right side of the FD to be a prime attribute. Thus, every left side of an FD in a table must be a superkey. Every table that is BCNF is also 3NF, 2NF, and 1NF, by the previous definitions.

### What are the benefits of BCNF and 3NF?

If a relation is in BCNF, it will satisfy 1NF, 2NF, and 3NF by default. It ensures that for every functional dependency X->Y, X is a super key of the table, making BCNF a stronger variation of 3NF.

**How does BCNF differ from 3NF explain with an example?**

The basic difference between 3NF and BCNF is that 3NF eliminates the transitive dependency from a relation and a table to be in BCNF, the trivial functional dependency X->Y in a relation must hold, only if X is the super key.

**Which is the strongest normal form in DBMS?**

The relation is in BCNF as all LHS of all Functional Dependencies are super keys. So, the highest normal form is BCNF.

#### Is 3NF always dependency preserving?

Let R be a relation. Now if we decompose it and make the decomposition 3NF, then it is possible to satisfy both lossless and dependency preserving. i.e., for any relation there always exist a decomposition to 3NF, which is guaranteed to satisfy both the given properties.

**How does BCNF decompose?**

Steps:

- Identify the dependencies which violates the BCNF definition and consider that as X->A.
- Decompose the relation R into XA & R-{A} (R minus A).
- Validate if both the decomposition are in BCNF or not. If not re-apply the algorithm on the decomposition that is not in BCNF.

**Is 3NF decomposition unique?**

Drawbacks of 3NF Decomposing Algorithm The result of the decomposing algorithm is not uniquely defined because a set of functional dependencies can hold more than one canonical cover.

## Why we use BCNF in DBMS?

BCNF (Boyce Codd Normal Form) is the advanced version of 3NF. A table is in BCNF if every functional dependency X->Y, X is the super key of the table. For BCNF, the table should be in 3NF, and for every FD. LHS is super key.

**Why BCNF is used in DBMS?**

BCNF was developed in 1974 by Raymond F. Boyce and Edgar F. Codd to address certain types of anomalies not dealt with by 3NF as originally defined. If a relational schema is in BCNF then all redundancy based on functional dependency has been removed, although other types of redundancy may still exist.

**What is BCNF in DBMS with example?**

### Which normalization is best in DBMS?

Normalization is a process of organizing the data in database to avoid data redundancy, insertion anomaly, update anomaly & deletion anomaly….Here are the most commonly used normal forms:

- First normal form(1NF)
- Second normal form(2NF)
- Third normal form(3NF)
- Boyce & Codd normal form (BCNF)

**Which is the weakest normal form in DBMS?**

Therefore, 2NF is the weakest normal form that the new database satisfies, but the old database does not.

**Is 3NF decomposition always lossless?**

The statement: 3NF ensures lossless decomposition while BCNF does not.

#### Why is BCNF not dependency preserving?

In BCNF, every non prime attribute should be functionally dependent on any of super key in schema. If there exists any FD, which don’t follow this, then for that case we have to separate it into new relation. Now if any of other FD uses previous FD, Then this creates non preservation of FD in BCNF.

**How do you decompose in 3NF?**

How to decompose this relation into 3NF relations?

- Find a minimal basis of F, say G.
- For each FD X → A in G, use {X, A} as the schema of one of the relations in the decomposition.
- If none of the sets of relations from Step2 is a superkey for R, add another relation whose schema is a key for R.

**Is BCNF always lossless?**

3NF ensures lossless decomposition while BCNF does not.

## Is BCNF decomposition unique?

No it’s not unique.

**What is the advantage of BCNF?**

It is a more restricted form of normalization so that the database does not end in anomalies. The business rules expressed in functional dependencies are enforced using keys, and BCNF ensures that it is correctly followed.

**What is BCNF decomposition?**

BCNF algorithm: It is used to decompose any given relation to BCNF directly. This algorithm gives guarantee for: Final BCNF decomposition. Lossless decomposition (Final BCNF decomposition will always be Lossless)

### Is 3NF good enough?

Normally 3NF good enough, but it really depends on your requirements. Be practical in your design.

**Why 3NF is better than 2NF?**

The relation R is in 2NF as no prime attribute is deriving non prime attribute that is there is no partial functional dependency….Difference between 2NF and 3NF :

S.NO. | 2NF(Second Normal Form) | 3NF(Third Normal Form) |
---|---|---|

4. | Stronger normal form than 1NF but lesser than 3NF | Stronger normal form than 1NF and 2NF. |