Trivial and Non Trivial Functional Dependency examples –
Trivial Functional Dependency –
Some functional dependencies are said to be trivial because they are satisfied by all relations. Functional dependency of the form A–>B is trivial if . or
A trivial Functional Dependency is the one where RHS is a subset of LHS.
Example, A>A is satisfied by all relations involving attribute A. SSN>SSN PNUMBER>PNUMBER SSN PNUMBER >PNUMBER SSN PNUMBER > SSN PNUMBER
Non Trivial Functional Dependency –
Non Trivial Functional Dependency can be categorized into –
 Complete Non Trivial Functional Dependency
 Semi Non Trivial Functional Dependency
Complete Non Trivial Functional Dependency – A Functional Dependency is completely non trivial if none of the RHS attributes are part of the LHS attributes.
Example, SSN > Ename,
PNUMBER > PNAME
PNUMBER> BDATE X
Semi Non Trivial Functional Dependencies – A Functional Dependency is semi non trivial if atleast one of the RHS attributes are not part of the LHS attributes.
{TRIVIAL + NONTRIVIAL}
Question 1 :

Identify Non Trivial Functional Dependency ?
Solution :

A→B is not a non trivial FD because, for 2, it has two outputs. i.e 2→2 and 2→3. for AB→C, 11→1, 12→1, 21→2, 22→3, so Non trivial.
Question 2: R(A B C D) AB {Candidate Key} A→C B→D . Where is the redundancy exist ?
Solution: (A C) and (B D) is suffering from redundancy.
Question 3: Consider a relation with schema R(A,B,C,D) and FDs {AB > C, C > D, D > A}. a. What are some of the nontrivial FDs that can be inferred from the given FDs?
Some examples:
C > ACD
D > AD
AB > ABCD
AC > ACD
BC > ABCD
BD > ABCD
CD > ACD
ABC > ABCD
ABD > ABCD
BCD > ABCD
Previous  Home  Next 
Types of FD with Example – 
Inference Rules For Functional Dependencies 
Incoming search terms:
 difference between trivial and non trivial dependencies
 trivial functional dependency
 trivial and non trivial dependencies
 Trivial dependency
 trivial and non trivial functional dependency in dbms
 trivial and non trivial dependency
 trivial and non trivial dependencies in dbms
 non trivial functional dependency
 functional dependencies in dbms
 trivial and non trivial functional dependency in dbms ppt