The number of selected games from a user (before payment) must not exceed the number of available stock.
Worth noting that the number of available stock must be dynamic cause there could be more than one user concurrently do shopping. So after a user paid and the stock is deducted permanently, then the available games for the other user who just selected must be updated.
The number of selected games from a user (before payment) must not exceed the number of available stock.
Worth noting that the number of available stock must be dynamic cause there could be more than one user concurrently do shopping. So after a user paid and the stock is deducted permanently, then the available games for the other user who just selected must be updated.