What do you mean by functional dependancy in dbms?

Answer 1

Dependency means that the one entity dependents on another entity. This is also applicable for the Function also.

For Example : If you trying to check the general function which tells you about the rooms availability, which consist of checkFreeRooms() and we can have the checkForACRooms() and CheckForSuits(), So the general function for checking Rooms dependents on the other rooms as above

Answer 2

1>Functional dependancies are constraints on the set of authorised relations.

2>In a particular relation say R attribute X is a functional dependant on attribute Y if every value in X in the relation has exactly one value of Y in the given relation.

3>The functional dependany is represented by:

X->Y

4>Which, implies that Y is functional dependent on X, or we say that X attibute functionally determines the attribute Y.