我之前的订单被最新订单覆盖

Question

我想循环代码让用户添加另一个项目。

我的任务是“开发一个程序，它将在订单后更新库存水平。在库存文件中包括当前库存水平，重新订购水平和目标库存水平。该程序应在指示时，计算哪些产品缺货或低于重新订购水平并创建一个文件。该文件将包含重新库存的订单，这些订单将使这些产品的当前库存水平达到目标库存水平“。我已经做了所有这些，但是我很难添加while循环，以防用户希望在他们的订单中添加另一个项目。

This is the stock file (this is named product information in the code)

This is the updated stock file when I run the code (this is named Blank file in the code)

This is the text file which contains orders for restocking (this is named Reorders in the code)

这是我的代码：

import csv
option='yes'
while option=='yes':
    data=open('Product information.csv', 'rt')
    purchase=csv.reader(data)
    blank=open('Blank file.csv', 'wt', newline='')
    blank_write=csv.writer(blank)
    reorder=open('Reorders.txt', 'wt')
    user_orders=[]
    order=input('Please enter the GTIN-8 code of the product you would like to purchase: ')
    quantity=int(input('Please enter the amount of this product you want to buy: '))
    for row in purchase:
        GTIN=row[0]
        item=row[1]
        price=row[2]
        stock=row[3]
        reorder_level=row[4]
        target_stock=row[5]
        if order==GTIN:
            stock=int(stock)-quantity
        blank_write.writerows([[GTIN,item,price,stock,reorder_level,target_stock]])
    data.close()
    blank.close()
    blank2=open('Blank file.csv', 'rt')
    blank_write2=csv.reader(blank2)
    choice=input('Please enter yes to check the current stock levels: ')
    if choice=='yes':
        for row in blank_write2:
            GTIN=row[0]
            item=row[1]
            price=row[2]
            stock=int(row[3])
            reorder_level=int(row[4])
            target_stock=int(row[5])
            if stock<=reorder_level:
                amount_to_restock=target_stock-stock
                reorder_file=('{} {} {} {} {} {} {}'.format(row[0]+'   ', row[1]+'   ', '{:10.2f}'.format(float(row[2]))+'   ', str(stock)+'   ', str(reorder_level)+'   ', str(target_stock)+'   ', str(amount_to_restock)))
                reorder.write(reorder_file)
    option=input('Would you like to add another item: ')
    if option=='no':
        blank2.close()
        reorder.close()

如果我输入“是否要添加其他项目”，则最新产品会覆盖我订购的第一个产品。这意味着只有最新产品才会写入CSV文件。我希望程序将这两个产品写入CSV文件。

由于