Sum of selected items

[MedAmineIT]

Hi 
in each order record i want to make a enum list of ref values from an other table (Products), i want to select multiple items from the droped list those items from products table which contain the following coloms : product id, product name , product price
now after selecting those products from the droped list i want to sum the price of them 
how  can i do that ?
thank you for your answer 

[wael]

Please create a VC called

Add the values through the new column with sum the price of them Inside it, it sums multiple values