Yes Gysbert I am getting the number of Sold Cars but how can i get the number of cars which were in stock.If i Write the expression Sum(Quantity) which is adding 140+139+138 of that same car.But i need to show it as if i have 140 as my intitial quantity and 3 cars are sold .To have the units in stock it should do as 140-3 which will be the units of stock.
Actually in the fact table it is like
Model_ID Customer_ID Quantity Units Sold
M001 2001 140 1
M001 2002 139 1
M001 2003 138 1.
Can you suggest an expression through which i can get the initial quantity-Sum(Units Sold)