Boyce Codd normal form (BCNF)BCNF is the advance version of 3NF. It is stricter than 3NF.A table is in BCNF if every functional dependency X → Y, X is the super key of the table.For BCNF, the table should be in 3NF, and for every FD, LHS is super key.Example: Let's assume there is a company where employees work in more than one department.EMPLOYEE...
08 April, 2022
Third Normal Form (3NF)
Third Normal Form (3NF)A relation will be in 3NF if it is in 2NF and not contain any transitive partial dependency.3NF is used to reduce the data duplication. It is also used to achieve the data integrity.If there is no transitive dependency for non-prime attributes, then the relation must be in third normal form.A relation is in third normal...
Second Normal Form (2NF)
Second Normal Form (2NF)In the 2NF, relational must be in 1NF.In the second normal form, all non-key attributes are fully functional dependent on the primary keyExample: Let's assume, a school can store the data of teachers and the subjects they teach. In a school, a teacher can teach more than one subject.TEACHER tableTEACHER_IDSUBJECTTEACHER_AGE25Chemistry3025Biology3047English3583Math3883Computer38In...
First Normal Form
First Normal Form (1NF)A relation will be 1NF if it contains an atomic value.It states that an attribute of a table cannot hold multiple values. It must hold only The first single-valued attribute.First normal form disallows the multi-valued attribute, composite attribute, and their combinations.Example: Relation EMPLOYEE is not in 1NF because...
Normalization
NormalizationNormalization is the process of organizing the data in the database.Normalization is used to minimize the redundancy from a relation or set of relations. It is also used to eliminate, undesirable characteristics like Insertion,...
Inference Rule
Inference Rule (IR):The Armstrong's axioms are the basic inference rule.Armstrong's axioms are used to conclude functional dependencies on a relational database.The inference rule is a type of assertion. It can apply to a set of FD(functional dependency) to derive other FD.Using the inference rule, we can derive additional functional dependency...
Functional Dependency
Functional DependencyFunctional dependency is a relationship that exists between two attributes. It typically exists between the primary key and non-key attribute within a table.X → Y The left...
