What is trivial dependency in DBMS?
The Trivial dependency is a set of attributes which are called a trivial if the set of attributes are included in that attribute. So, X -> Y is a trivial functional dependency if Y is a subset of X.
What is trivial and non trivial functional dependency with example?
By Chaitanya Singh | Filed Under: DBMS. If a functional dependency X->Y holds true where Y is not a subset of X then this dependency is called non trivial Functional dependency. For example: An employee table with three attributes: emp_id, emp_name, emp_address.
What is trivial and nontrivial dependency?
Trivial − If a functional dependency (FD) X → Y holds, where Y is a subset of X, then it is called a trivial FD. Trivial FDs always hold. Non-trivial − If an FD X → Y holds, where Y is not a subset of X, then it is called a non-trivial FD.
Why some functional dependencies are called trivial?
Answer: Certain functional dependencies are called trivial functional depen- dencies because they are satisfied by all relations.
What do you mean by trivial functional dependency give an example?
The Trivial dependency is a set of attributes which are called a trivial if the set of attributes are included in that attribute. So, X -> Y is a trivial functional dependency if Y is a subset of X. For example: Emp_id.
What is join dependency with example?
Join dependency is a constraint which is similar to functional dependency or multivalued dependency. It is satisfied if and only if the relation concerned is the join of a certain number of projections. Such type of constraint is called join dependency….Relation R.
What is trivial attribute?
Trivial or irrelevant attributes are defined as attributes that do not create a meaningful difference in a brand’s performance.
Which of the following is trivial functional dependency?
In Trivial Functional Dependency, a dependent is always a subset of the determinant. Similarly, roll_no → roll_no is also an example of trivial functional dependency.
What is functional dependency give example?
A functional dependency (FD) is a relationship between two attributes, typically between the PK and other non-key attributes within a table. For any relation R, attribute Y is functionally dependent on attribute X (usually the PK), if for every valid instance of X, that value of X uniquely determines the value of Y.
What is a functional dependency with example?
A Functional dependency is a relationship between attributes. In functional dependency we can obtain the value of another attribute from given attribute. For example, If we know the value of student roll number, we can obtain student address, marks etc.
What are non trivial functional dependencies?
Non-trivial Functional Dependency In Non-trivial functional dependency, the dependent is strictly not a subset of the determinant. i.e. If X → Y and Y is not a subset of X, then it is called Non-trivial functional dependency.
What is trivial join dependency?
A table T is subject to a join dependency if T can always be recreated by joining multiple tables each having a subset of the attributes of T. A trivial join dependency is defined as follows: If one of the tables in the join has all the attributes of the table T, the join dependency is called trivial.