Functional Dependency
A functional dependency A->B in a relation holds if two tuples having the same value of attribute A also have the same value for attribute B. For Example, in relation to STUDENT shown in Table 1, Functional Dependencies
STUD_NO->STUD_NAME, STUD_NO->STUD_PHONE hold
but
STUD_NAME->STUD_STATE do not hold
Student Table
Advantages of Functional Dependencies
- Through the identification and removal of redundant or unneeded data, they aid in the reduction of data redundancy in databases.
- By guaranteeing that data is correct and consistent throughout the database, they enhance data integrity.
- They make it simpler to add, edit, and remove data, which helps with database management.
Disadvantages of Functional Dependencies
- The process of identifying functional dependencies can be time-consuming and complex, especially in large databases with many tables and relationships.
- Overly restrictive functional dependencies can result in slow query performance or data inconsistencies, as data that should be related may not be properly linked.
- Functional dependencies do not take into account the semantic meaning of data, and may not always reflect the true relationships between data elements.
Functional Dependency and Attribute Closure
Fundamental ideas in database management and design are functional dependency and attribute closure. They are essential to maintaining data integrity and building effective, organized, and normalized databases.