Multivalued Dependency (MVD)

Multivalued Dependency (MVD)

A Multivalued Dependency (MVD) occurs in a relational database when one attribute determines multiple independent values of another attribute. It is represented as A →→ B, which means that for a single value of attribute A, there can be multiple values of attribute B, and these values are independent of other attributes in the relation. Multivalued dependency usually arises when a table contains two or more attributes that depend on the same key but are not related to each other. This situation can lead to data redundancy and unnecessary repetition of records, causing insertion, deletion, and update anomalies. To eliminate multivalued dependencies, the relation is decomposed into smaller tables following the rules of Fourth Normal Form (4NF). Handling MVD properly helps in designing efficient, consistent, and well-structured database systems.

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