Contents
Where this relation is in 3NF or not?
A relation will be in 3NF if it is in 2NF and not contain any transitive partial dependency. 3NF is used to reduce the data duplication. It is also used to achieve the data integrity….EMPLOYEE table:
| EMP_ID | EMP_NAME | EMP_ZIP |
|---|---|---|
| 666 | John | 462007 |
How do you identify transitive dependency?
When an indirect relationship causes functional dependency it is called Transitive Dependency. If P -> Q and Q -> R is true, then P-> R is a transitive dependency. To achieve 3NF, eliminate the Transitive Dependency.
In which normal form the transitive dependency is taken care?
Third Normal Form
A relation that is in First and Second Normal Form and in which no non-primary-key attribute is transitively dependent on the primary key, then it is in Third Normal Form (3NF). Note – If A->B and B->C are two FDs then A->C is called transitive dependency.
Can primary key be transitive dependency?
Transitive dependency occurs only if you have indirect relationship between more than 2 attributes that are not part of they key. In your example, as you explained, the StaffID is part of your dependency, which is fine because it’s the primary key.
Why is transitive dependency bad?
Why Transitive Dependencies Are Bad Database Design This kind of design can contribute to data anomalies and inconsistencies, for example: Having multiple records with the same author can result in inaccurate data.
What do you mean by transitive dependency?
A transitive dependency in a database is an indirect relationship between values in the same table that causes a functional dependency. To achieve the normalization standard of Third Normal Form (3NF), you must eliminate any transitive dependency.
Third Normal Form deals with something called ‘transitive’ dependencies. This means if we have a primary key A and a non-key domain B and C where C is more dependent on B than A and B is directly dependent on A, then C can be considered transitively dependant on A. Another way to look at it is a bit like a stepping stone across a river.
When is a relation in third normal form?
A relation is in third normal form, if there is no transitive dependency for non-prime attributes as well as it is in second normal form. A relation is in 3NF if at least one of the following condition holds in every non-trivial function dependency X –> Y: X is a super key. Y is a prime attribute (each element of Y is part of some candidate key).
When to use third normal form ( 3NF )?
X is a super key. Y is a prime attribute (each element of Y is part of some candidate key). A relation that is in First and Second Normal Form and in which no non-primary-key attribute is transitively dependent on the primary key, then it is in Third Normal Form (3NF). Note – If A->B and B->C are two FDs then A->C is called transitive dependency.
How do you remove a transitive dependency from a relation?
If a transitive dependency exists, we remove the transitively dependent attribute (s) from the relation by placing the attribute (s) in a new relation along with a copy of the determinant. Consider the examples given below.