In the context of relational databases, functional dependency is a relationship between two attributes (or columns) in a relation (or table), in which the value of one attribute determines the value of another attribute.
Formally, we say that attribute A is functionally dependent on attribute B if, for every value of B, there is a unique value of A. This is denoted as B → A.
For example, consider a table named "employees" with columns "employee_id", "employee_name", and "department_name". In this table, we can say that "department_name" is functionally dependent on "employee_id" because for every unique "employee_id", there is a unique "department_name" associated with it.
Functional dependencies are important in database design because they help to ensure that the data in a relation is well-formed and free from redundancy. By identifying the functional dependencies in a relation, we can determine the minimal set of attributes required to represent the data, and eliminate any redundant or unnecessary attributes.
Functional dependencies are also used in normalization, which is a process of refining a relation into smaller, well-organized relations, to minimize data redundancy and improve data integrity.
A Functional dependency is denoted by X Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R. The constraint is for any two tuples t1 and t2 in r if t1[X] = t2[X] then they have t1[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component Y.
Liked By
Write Answer
What is Functional Dependency?
Join MindStick Community
You have need login or register for voting of answers or question.
Aryan Kumar
28-Apr-2023In the context of relational databases, functional dependency is a relationship between two attributes (or columns) in a relation (or table), in which the value of one attribute determines the value of another attribute.
Formally, we say that attribute A is functionally dependent on attribute B if, for every value of B, there is a unique value of A. This is denoted as B → A.
For example, consider a table named "employees" with columns "employee_id", "employee_name", and "department_name". In this table, we can say that "department_name" is functionally dependent on "employee_id" because for every unique "employee_id", there is a unique "department_name" associated with it.
Functional dependencies are important in database design because they help to ensure that the data in a relation is well-formed and free from redundancy. By identifying the functional dependencies in a relation, we can determine the minimal set of attributes required to represent the data, and eliminate any redundant or unnecessary attributes.
Functional dependencies are also used in normalization, which is a process of refining a relation into smaller, well-organized relations, to minimize data redundancy and improve data integrity.
Sumit Kesarwani
22-Sep-2014A Functional dependency is denoted by X Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R. The constraint is for any two tuples t1 and t2 in r if t1[X] = t2[X] then they have t1[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component Y.