UnboundLocalError：局部變量「Core_prices」引用之前分配

Question

我用一個函數計算服務器的價格，所以我做這檢索服務器組件的defalut價格，並計算服務器的價格在我的數據庫的每臺服務器exsit功能，但我嘗試運行這個功能，我得到這個錯誤：

function.py 

import MySQLdb 

def calculations_metric (param) : 
    db = MySQLdb.connect("localhost", "root", "aqw", "PFE_Project") 
    cursor = db.cursor() 
    sql = "SELECT * FROM examples_calculationsmetric" 
    cursor.execute(sql) 
    results = cursor.fetchall() 
    for row in results: 
     RAM_prices = int(row[1]) 
     Core_prices = int(row[2]) 
     HHD_SATA_prices =int(row[3]) 
     HHD_SSD_prices =int(row[4]) 
     CPU_priority = int(row[5]) 
     Avaibility = int(row[6]) 
    db.close() 

    db1 = MySQLdb.connect("localhost", "root", "aqw", "PFE_Project") 
    cursor1 = db1.cursor() 
    sql1 = "SELECT * FROM examples_servercomponents WHERE id ='%d'" %(param) 
    cursor1.execute(sql1) 
    results1 = cursor1.fetchall() 
    for row in results1: 
     if row[6] == 'SATA': 
      Core_price = int(row[2]) * Core_prices # the error is here 
      Priority_price = int(row[3]) * CPU_priority 
      RAM_price = int(row[4]) * RAM_prices 
      HDD_price = int(row[5]) * HHD_SATA_prices 
      Availibility_price = int(row[7])*Avaibility 

     elif row[6] == 'SSD': 
      Core_price = int(row[2]) * Core_prices 
      Priority_price = int(row[3]) * CPU_priority 
      RAM_price = int(row[4]) * RAM_prices 
      HDD_price = int(row[5]) * HHD_SSD_prices 
      Availibility_price = int(row[7])*Avaibility 

    price = Core_price + Priority_price + RAM_price + HDD_price + Availibility_price 
    db1.close() 
    return price 

我不明白什麼是錯誤，所以如果誰能幫助我會如此感激

Answer 1

當你的SELECT * FROM examples_calculationsmetric不返回任何結果，Core_prices是從來沒有設置（也沒有在該循環中的其他變量）。不存在

Python的名字，直到分配，因此，如果results是一個空單，for循環內的名字永遠不會分配，因此並沒有通過的時候，你遍歷results1後存在。

您可以爲這些名稱默認值設置爲一個變通：

RAM_prices = 0 
Core_prices = 0 
HHD_SATA_prices = 0 
HHD_SSD_prices = 0 
CPU_priority = 0 
Avaibility = 0 

至少確保它們被定義。