Domain-Key Normal Form

DBMSDatabaseMySQL

A relation is in DKNF when insertion or delete anomalies are not present in the database. Domain-Key Normal Form is the highest form of Normalization. The reason is that the insertion and updation anomalies are removed. The constraints are verified by the domain and key constraints.

A table is in Domain-Key normal form only if it is in 4NF, 3NF and other normal forms. It is based on constraints −

Domain Constraint

Values of an attribute had some set of values, for example, EmployeeID should be four digits long −

EmpIDEmpNameEmpAge
0921Tom33
0922Jack31


Key Constraint

An attribute or its combination is a candidate key

General Constraint

Predicate on the set of all relations.

Every constraint should be a logical sequence of the domain constraints and key constraints applied to the relation. The practical utility of DKNF is less.

raja
Published on 03-Jul-2018 20:31:40
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