public void addProductVisibleDiscount(int product, int session, double percentage, string duration)
{
if (percentage <= 0 || percentage >= 1)
{
throw new IllegalAmountException("percentage of discount must be a number between 0 to 1");
}
if (product < 0)
{
throw new ILLArgumentException("illegal product number");
}
if (session < 0)
{
throw new NullReferenceException("session is a null reference");
}
db.addProductVisibleDiscount(product, percentage, duration, session);
}
