Hello all,
People who can buy something from me have a customer account with a “credit”. It is normal that this field is in the minus. So a drink that costs 1,70€ must be booked as minus. So the “credit” should be -1,70€. How can I change the sign when booking the item?
With the button “book” I have a change in the current user. First I get the current “credit” “Current Users’s credit” and book to it the articles he has ordered “Calculate SumProduct”.
Thank you 
Multiply the expression with - 1
Do you have an example? I don’t now how it works. Thank you
Calculate Sum product * -1
Actually why aren’t you just doing credit = Current user’s credit - Calculate Sum product? That’s logically equivalent to Current user’s credit + Calculate Sum product * -1
The credit could be a positive or negativ value. That’s the reason why
But you’re calculating this sum product on a shopping cart… surely that’s always positive as products can’t have a negative value?
Then Current user’s credits - Cart’s sum product is always correct.
