Explain the difference between functional dependencies that arise from equations and those that do not.

Functional dependencies are used to uniquely relate different attributes to other attributes. Their main use is in the case of arithmetic operations when they are carried out by fetching data from different databases with the help of different computer languages. For example the net salary = total salary – tax, means that net salary is the outcome of the total salary – taxes in the given equations. Net salary is dependent on total salary and the tax deductions.

Functional dependencies may not arise from equations. For example last name of father = last name of the son is not a dependency that is explained by an equation.