Please visit, subscribe and share 10 Minutes Lectures in Computer Science

Thursday, 11 February 2016

Full partial transitive and multivalued function dependencies

Set of keywords about functional dependencies used in Normalization process / Set of functional dependencies that you need to know in Normalization process / Full functional dependency / Partial functional dependency/ Transitive Dependency / Multi-valued dependency / Functional dependencies in Normalization process / Define Full, partial, transitive, and multi-valued function dependencies

Various Types of Functional Dependencies used in Normalization Process 

Full Functional Dependency – Click here to read more…

Definition 1:
If X is a set of attributes and Y is another set of attributes, then any functional dependency such that X → Y is said to be a full functional dependency if and only if all the attributes of Y is functionally dependent on complete X.
In other words, X → Y becomes invalid if we remove any attribute from X.
Definition 2:
A functional dependency X → Y is a full functional dependency if removal of any attribute from A results in the dependency no longer existing
Functional Dependency – Click to read more…

Functional dependency is a constraint (condition) that describes the relationship between two sets of attributes. It is written as X → Y. it can be read as, the values of X determine the values of Y uniquely, or the values of Y are uniquely determined by the values of X, or Y is functionally dependent on X. Here, X is determinant, and Y is dependent.
Multi-valued Dependency– Click to read more…

Partial Dependency Click to read more…

It is a type of functional dependency where a non-key (non-prime) attribute is functionally dependent on a subset of the primary key (or candidate key) attribute.
For example, we would say that a functional dependency XY → A as a partial functional dependency, if there exists other FDs like X → A or Y → A.
In other words, removal of Y from X → A or removal of X from Y → A still holds the dependency.
Transitive Dependency – Click to read more…

Dependency of a non-key attribute (or set of non-key attributes) on another non-key attribute (or set of non-key attributes) is called transitive dependency. For example, if X → Y and  Y → Z holds in a relation R(X, Y, Z), then these FDs imply X → Z (through transitivity axiom). Then X → Z is called transitive dependency.
Trivial Functional Dependency – Click to read more…

The dependency of an attribute (or set of attributes) on a set of attributes is called trivial functional dependency if the set of attributes on the Left Hand Side (LHS) of the functional dependency contains RHS attributes.
In other words, a functional dependency A → B is said to be trivial if B is subset or equal to A. Other examples are X → X, Y → Y, AB → AB etc.

Go back to NORMALIZATION keywords page

No comments:

Post a Comment

Featured Content

Multiple choice questions in Natural Language Processing Home

MCQ in Natural Language Processing, Quiz questions with answers in NLP, Top interview questions in NLP with answers Multiple Choice Que...

All time most popular contents