Formula triggers:

Formula triggers are PL/SQL functions which populate columns of type formula. The pl/sql function is needed for any column of type formula. A data type of the formula column determines the return data type for the formula trigger. An instance of a formula trigger is as given below:

Function radiant Return Number is
Begin
Return    :avg_product_rate * :sum_quantity;
End;

Formula triggers are created as the name of the formula column followed through the reserve word formula. The value returned through the formula trigger is displayed in the report field connected to the formula column.