Defining functional dependency (Dependence).
Explanation of Solution
The functional dependency is a relationship between two attributes, generally between primary key and other non-key attributes within a table.
Consider a relation R where the attribute B is functionally dependent on the attribute A (usually the primary key).
It can be written as follows:
The left side in the above relation is called as the determinant and the right side is known as the dependent (Functional dependency). If A can determine the value of B then it means that if value of A is knowing one get the value of B without ambiguity.
For Example, consider a table with attributes StudentID, Name, Class, DateOfBirth where the StudentID (Primary key) determines the Name, Class and DateOfBirth :
StudentID | Name | Class | DateOfBirth |
001 | Chris | 5 | 09/11/2011 |
002 | David | 6 | 02/02/2010 |
003 | Johana | 7 | 08/05/2011 |
Table 1
Table 1 shows the key attribute that is StudentID, which determines the Name, Class and DateOfBirth.
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