How to Find Non Trivial Functional Dependencies

Ive probably watched most of the material available but still fail to understand what a non trivial FD is. If there is a dependency in a database such that attribute B is dependent upon attribute A you would write this as.

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We can define Non-trivial functional dependency in two ways.

. To distinguish trivial and non-trivial functional dependencies first check if the dependent is subset of determinant or not if dependent is subsetnot necessary a proper subset then it is trivial dependency otherwise the functional dependency is non-trivialsuccessively you can count the number of functional dependencies whether trivial or non-trivialFor example- A functional. Find number of candidate keys given non-trivial functional dependency X-Y where X is some set of attributes and Y is some prime attribute 0 Figuring out the equivalence between two definitions of transitive functional dependencies and intuition behind the intended meaning of definition. Finding out the set of possible functional dependencies.

It can also be defined as when at least one attribute in the right side of FD is not a part of the left side of FD. An employee table with three attributes. So to find non-trivial FD you have to just count such FD s who satisfy the above condition.

Types of Functional Dependencies. DeptId Department ID. X Y ɸ.

For example in a table listing employee characteristics including Social Security number SSN. Four types of functional dependency are 1 Multivalued 2 Trivial 3 Non-trivial 4 Transitive. The following is an example that would make it easier to understand functional dependency.

If an FD X Y holds where Y is not subset of X then it is called non-trivial FD. Functional Dependency is when one attribute determines another attribute in a DBMS system. AFind a nontrivial functional dependency containing no extraneous attributes that is logically implied by the above three dependencies and explain how you found it.

Emp_id emp_name - emp_name emp_name is. When A intersection B is NULL then A B is called as complete non-trivial. Axiom Decomposition Dependent Determinant Union are key terms for functional dependency.

Thus if there exists at least one attribute in the RHS of a functional dependency that is not a part of LHS then it is called as a non-trivial functional dependency. X b c and Y b a. BUse the BCNF decomposition algorithm to find a BCNF decomposition of R.

DeptName Department Name. A B has a non-trivial functional dependency if B is not a subset of A. Example for condition 1.

This is an example to complement this correct answer. Functional dependency which also known as a nontrivial dependency occurs when A-B holds true where B is not a subset of A. A Non Trivial Functional Dependency is a normal functional dependency where the non-key attribute is functionally dependent on a primary key attribute without the occurrence of trivial functional dependency.

Y is said to bea non-trivial functional dependency if and only if Y is not a subset of X ie Y. The DeptId is our primary key. Here roll_no name is a non-trivial functional dependency since the dependent name is not a subset of determinant roll_no Similarly roll_no name age is also a non-trivial functional dependency since age is not a subset of roll_no name.

So the valid attribute we can have in either side is given below. Non-Trivial Functional Dependencies- A functional dependency X Y is said to be non-trivial if and only if Y X. Student_id Name - student_id is a trivial functional dependency as student_id is a subset of student_idName.

A functional dependency will have Left side that is A here and Right side that is B here. For A Y Z and B Y X and if A-B then we have that A-B is non-trivial and that A-B is not completely-non trivial. Sid Cname - There is no common attribute between Sid and Cname because both are single unique attribute so it satisfies condition 1 Sid Cname ɸ.

X Y. This is the explanation ive seen. Just to make it clear If a functional dependency X Y holds where Y is a subset of X then it is called a trivial FD.

In a relationship if attribute B is not a subset of attribute A then it is considered as a non-trivial dependency. Here DeptId uniquely identifies the DeptName attribute. Non-Trivial Functional Dependency in DBMS.

Oldest Newest Vote View More Answers. If X Y then the FD is non-trivial but not completely non-trivial. Also Employee_Id Employee_Id and Employee_Name Employee_Name are trivial dependencies too.

X Y where is a non-trivial functional dependency if and only if Y is not a subset of X. Start with A BC. These videos are useful for examinations like NTA UGC NET Computer Science and Applications GATE Computer Science ISRO DRDO Placements etc.

The following functional dependencies are non-trivial. In contrast if Y is NOT a subset of X then it is a non-trivial functional dependency. What are trivial non trivial and semi trivial Functional Dependencies.

We have a table with two attributes DeptId and DeptName. Saying that there is a dependency between attributes in a table is the same as saying that there is a functional dependency between those attributes. Assume the functional dependency as AB.

Non Trivial Functional Dependency in DBMS. If you want. Show activity on this post.

Emp_id - emp_name emp_name is not a subset of emp_id emp_id - emp_address emp_address is not a subset of emp_id On the other hand the following dependencies are trivial. If i want to find all the non-trivial FDs in my example below how should i think about it.

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