在我的python程序中获取类型错误？

错误：

import sqlite3

Book = sqlite3.connect("BookStore.db")
curbook = Book.cursor()
more=True
total_cost = 0.0
while(more):   
    Title = input("Enter Title of the book : ")
    curbook.execute("SELECT title,author,price FROM BookDetails WHERE title = '"+ Title +"';")
    record = curbook.fetchone()
    if record ==  None:
        print("No Record Found")
        break
    else :  
        print(record)
        no_of_copies = int(input("Enter Number of copies you want to purchase : "))
        More = input("Add more books? Y/N")
        if More == 'n' or More == 'N':
            more = False
        curbook.execute("SELECT price from BookDetails WHERE title = '"+ Title +"';")
        price = curbook.fetchone()
        total_cost = total_cost + no_of_copies * price
        print("Total Cost ",total_cost)
Book.close()

价格是一个元组

尝试：

---

正如错误所述，no_of_copies或price是一个元组而不是float.fetchone返回一个元组，其中包含所需列中的数据。即使只有一列，它仍然返回一个元组。所以价格是一个元组。使用price[0]尝试打印price，您会看到一个元组ex:10，您可以使用索引访问该元素

Traceback (most recent call last):
  File "C:\Python35\Retrieve_Book.py", line 21, in <module>
    total_cost = total_cost + no_of_copies * price
TypeError: unsupported operand type(s) for +: 'float' and 'tuple'

total_cost = total_cost + no_of_copies * price[0]