Answer to Question #50242 in Engineering for Sam

Question

Given the following relational instance,
A B C
1 2 3
3 1 2
1 3 2
4 1 5
Which of the following functional dependencies are
satisfied?
i) A -> B
ii) B -> C
iii) A-> C

Answer 1

A functional dependency is a constraint between two sets ofattributes in a relation from a database.
Given a relation R, a set ofattributes X in R is said to functionally determine another
set of attributes Y, also in R, (written X → Y) if,
and only if, each X value is associated with precisely one Y
value; R is then said to satisfy the functional
dependency X → Y.
So, in our case, dependency A-> C is
satisfied.
That's why, the right answer is
iii) A-> C