ValueError:无法在Python/MySQL中处理参数 [英] ValueError: Could not process parameters in Python/MySQL

问题描述

我是新手

我想防止每次注册时重复的用户名.

I want to prevent the duplicate usernames every time people do registration.

这是我的摘录代码:

def submit(self):
    username_info = username.get()
    username_password = password.get()

    #connect to db
    db = mysql.connector.connect(host = 'localhost', user = 'root', password = '', database = 'user')

    #create a cursor
    mycursor = db.cursor()
    #insert to db
    sql = ("INSERT INTO useraccess (user_type, password) VALUES (%s, %s)")

    query = (username_info, username_password)
    mycursor.execute(sql, query)
    #commit
    db.commit()

    #create a messagebox
    messagebox.showinfo("Registration", "Successfully Register")

    #if username has been used
    find_user = ("SELECT * FROM useraccess WHERE user_type = ?")
    user_query = (username_info)

    mycursor.execute(find_user, user_query)
    #if (username == username_info):
    if mycursor.fetchall():
        messagebox.showerror("Registration", "The username chosen is already used. Please select another username")
    else:
        messagebox.showinfo("Registration", "Account Created!")

但是每次我运行它时，尽管用户名已在数据库中注册，但它仅显示成功创建的消息框和错误:

But every time I run it, although the username has been registered in the db, it only shows the successfully created messagebox and error:

ValueError:无法处理参数.

ValueError: Could not process parameters.

任何人都可以帮助我解决这个问题吗?

Anyone can help me to solve this problem?

推荐答案

我相信问题的根源所在

user_query = (username_info)

应该是

user_query = (username_info,)

结尾的逗号是括号中的表达式与元组.

The trailing comma is the syntactic difference between an expression in parentheses and a tuple.

代码的另一个问题是查询:

Another issue with code is the query:

find_user = ("SELECT * FROM useraccess WHERE user_type = ?")

应为:

find_user = ("SELECT * FROM useraccess WHERE user_type = %s")

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