Next, we update the bills again, setting the total bill to the price minus the discount plus the sales tax, which is read from the state table. 接下来,再次更新账单,将总账单设置为价格减去折扣和销售税,这从state表读取。
If we look at the update of the bill_items, all we are doing is updating a discount based on information from the customer table, which we had when we first built the bill_items table. 如果我们看一下对billitems的更新,我们所做的就是基于来自customer表的信息来更新discount,这个我们在首次构建billitems表时已经掌握了。