A formula calculation assigns a value to a calculated item by performing calculations involving one or more bind variables or constants. Bind variables include form items, parameters, global variables, and system variables.
Calculation Expression
To define the calculation that will assign values to a formula item, you must provide a single PL/SQL expression in the item's Formula property. The expression you write can reference Built-in or user-written subprograms.
You cannot enter an entire PL/SQL statement in the Formula property field. Oracle Forms adds the actual assignment code to the formula internally, so do not add the code yourself or terminate your calculation expression with a semicolon. For example, if you set the Formula property to the expression:
:emp.sal + :emp.comm
Oracle Forms will internally convert this into a complete statement:
:emp.gross_comp := (:emp.sal + :emp.comm);
Null Value. The value of a formula item is NULL if: