如果 mySQL 数据库中已经存在用户名和密码，我如何在 python 中进行验证？

Question

嗨，我已经在这个项目上工作了大约一天（python 和 mySQL 的新手） 所以我的问题是如何查看文本框中的输入用户凭据是否已经是注册用户？

到目前为止，我已经设法将它连接到数据库并在数据库中存储一些值，但我似乎无法弄清楚如何扫描该数据库并查看按下登录按钮时用户信息是否有效。

from tkinter import*
from tkinter import messagebox
import mysql.connector
import time
import datetime
import random

w = 300
h = 2

def register_user():

    global username_info
    global password_info

    if len(username.get()) == 0 and len(password.get()) == 0:
        print("Please fill in the Missing Info")

    if len(username.get()) == 0 and len(password.get()) != 0 :
            print("Please Enter a Username")
    elif len(username.get()) != 0 and len(password.get()) == 0:
                    print("Please enter a Password")


    else:
        username_info = username.get()
        password_info = password.get()

        mydb = mysql.connector.connect(
            host="localhost",
            user="root",
            passwd="root",
            database="loginsystem"
        )
        mycursor = mydb.cursor()
        sqlFormula = "INSERT INTO users (Username, Password) VALUES (%s, %s)"
        insertvar = (username_info, password_info)
        user1 = ("Joshua", "Cuyugan")
        mycursor.execute(sqlFormula, insertvar)
        mydb.commit()

        username.set("")
        password.set("")

def register():
    global screen1

    screen.withdraw()
    screen1 = Toplevel(screen)
    screen1.title("Registration")
    screen1.geometry("500x250+700+350")

    global username
    global password
    global username_entry
    global password_entry

    username = StringVar()
    password = StringVar()

    Label(screen1, text = " Please Enter Your Details Below", bg = "black", width = w , height = h, font = ("Calibri", 20) , fg = "white").pack()
    Label(screen1, text = "").pack()
    Label(screen1, text = "Username").place(x=220, y=85)
    username_entry = Entry(screen1, textvariable = username, width="50").place(x=100, y=110)
    Label(screen1, text = "Password").place(x=220, y=135)
    password_entry = Entry(screen1, textvariable = password, width="50").place(x=100, y=160)
    Button(screen1, text= "Register", height="1", width="20", command = register_user).place(x=80, y=200)
    Button(screen1, text="Cancel", height="1", width="20", command= on_closereg).place(x=270, y=200)


    screen1.protocol("WM_DELETE_WINDOW", on_closereg)



def login():
    global screen2

    mydb = mysql.connector.connect(
        host="localhost",
        user="root",
        passwd="root",
        database="loginsystem"
    )
    mycursor = mydb.cursor()
    sql_select_Query = "select * from users"
    mycursor.execute(sql_select_Query)
    records = mycursor.fetchall()
    for row in records:
        print("Username" , row[1],)
        print("Password", row[2], "\n" )
        mycursor.close()

    screen.withdraw()
    screen2 = Toplevel(screen)
    screen2.title("HOT or SUPER HOT")
    screen2.geometry("800x600+550+220")


    screen2.protocol("WM_DELETE_WINDOW", on_close)

def checker():
    if len(username.get()) == 0 and len(password.get()) == 0:
        print("Please fill in the Missing Info")


def on_close():
    screen2.withdraw()
    screen.update()
    screen.deiconify()
    screen.lift()

def on_closereg():
    screen1.withdraw()
    screen.update()
    screen.deiconify()
    screen.lift()

def verify():
    global name
    global userlogcred
    global userpascred

    userlogcred = username_verify.get()
    userpascred = password_verify.get()

    loadname = ("SELECT Username FROM users WHERE Username =%s")
    loadpass = ("SELECT Password FFROM users WHERE Password =%s")

    mydb = mysql.connector.connect(
        host="localhost",
        user="root",
        passwd="root",
        database="loginsystem"
    )
    mycursor = mydb.cursor()

    if len(username_verify.get()) == 0 and len(password_verify.get()) == 0:
        print("Please fill in the Missing Info")
    if len(username_verify.get()) == 0 and len(password_verify.get()) != 0 :
        print("Please Enter a Username")
    elif len(username_verify.get()) != 0 and len(password_verify.get()) == 0:
        print("Please enter a Password")

    else:
        mycursor.execute(loadname, userlogcred)
        mycursor.execute(loadpass, userpascred)
        logincheck = mycursor.fetchone()
        loginpasscheck = mycursor.fetchone()
        if logincheck is None:
            print("Sorry, could not find you in the database\nOr it just isn't working")
        if logincheck is not None and loginpasscheck is None:
            print("Please Enter your Password")
        elif logincheck is None and loginpasscheck is not None:
            print("Please enter Your Username")
        else:
            print("pass\nSuccessfully loaded {} from the database".format(username_verify.get()))



def main_Screen():

    global screen

    screen = Tk()
    screen.geometry("600x300+650+350")
    screen.title("Login System")


    Label(text = "Login System" , bg = "black", width = w , height = h, font = ("Calibri", 20) , fg = "white").pack()
    Label(text = "").pack()
    Button(text = "Login", height = h, width = "30", command = verify).place(x=50 , y=200)
    Label(text = "").pack()
    Button(text = "Register" ,height = h, width = "30", command = register).place(x=320 , y=200)


    global username_verify
    global password_verify

    username_verify = StringVar()
    password_verify = StringVar()
    Label(screen, text = "Username").place(x=265, y = 90)
    username_entry1 = Entry(screen, textvariable = username_verify, width = "80").place(x=57, y=110)
    Label(screen, text="Password").place(x=267, y=140)
    password_entry1 = Entry(screen, textvariable = password_verify, width = "80").place(x=57, y=160)

    screen.mainloop()


main_Screen()

print("Hello World")

更新我找到了这个代码，我正在尝试将它应用到我的项目中，在这个代码中，将文本框中的输入值与数据库数据进行比较，并检查数据是否已经存在，然后发送给你到另一种形式。

def verify():
    global name

    loadname = ("SELECT Username FROM users WHERE Username =%s")
    loadpass = ("SELECT Password FFROM users WHERE Password = %s")

    mydb = mysql.connector.connect(
        host="localhost",
        user="root",
        passwd="root",
        database="loginsystem"
    )
    mycursor = mydb.cursor()

    if len(username_verify.get()) == 0 and len(password_verify.get()) == 0:
        print("Please fill in the Missing Info")

    if len(username_verify.get()) == 0 and len(password_verify.get()) != 0 :
            print("Please Enter a Username")
    elif len(username_verify.get()) != 0 and len(password_verify.get()) == 0:
                    print("Please enter a Password")

    else:
        mycursor.execute(loadname, username_verify.get())
        mycursor.execute(loadpass, password_verify.get())
        logincheck = mycursor.fetchone()
        loginpasscheck = mycursor.fetchone()
        if logincheck is None:
            print("Sorry, could not find you in the database\nOr it just isn't working")
        if logincheck is not None and loginpasscheck is None:
            print("Please Enter your Password")
        elif logincheck is None and loginpasscheck is not None:
            print("Please enter Your Username")
        else:
            print("pass\nSuccessfully loaded {} from the database".format(login))

但我遇到了这个错误，请帮忙。

Traceback (most recent call last):
  File "C:\Users\lenovo\AppData\Local\Programs\Python\Python37-32\lib\tkinter\__init__.py", line 1705, in __call__
    return self.func(*args)
  File "C:/Users/lenovo/PycharmProjects/Pylog/App.py", line 141, in verify
    mycursor.execute(loadname, username_verify.get())
  File "C:\Users\lenovo\PycharmProjects\Pylog\venv\lib\site-packages\mysql\connector\cursor.py", line 569, in execute
    self._handle_result(self._connection.cmd_query(stmt))
  File "C:\Users\lenovo\PycharmProjects\Pylog\venv\lib\site-packages\mysql\connector\connection.py", line 553, in cmd_query
    result = self._handle_result(self._send_cmd(ServerCmd.QUERY, query))
  File "C:\Users\lenovo\PycharmProjects\Pylog\venv\lib\site-packages\mysql\connector\connection.py", line 442, in _handle_result
    raise errors.get_exception(packet)
mysql.connector.errors.ProgrammingError: 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '%s' at line 1
Hello World

更新我将username_verify.get() 值放入变量中仍然不起作用，它仍然发布相同的错误。

Answer 1

import mysql.connector as sql

class connections:
    __HOST = 'localh`o`st'
    __USERNAME = 'root'
    __PASSWORD = ''
    __DATABASE = 'testing'
    
    def __init__(self):
        self.con = sql.connect(host=connections.__HOST,user=connections.__USERNAME,password=connections.__PASSWORD,database=connections.__DATABASE)


    def connect_database(self,username,password):
        #append password and username in the emptey list below for later checkings
        mypassword_queue =[]
        sql_query = "SELECT *FROM users WHERE first_name ='%s' AND password ='%s'" % (username, password)
        mycursor = self.con.cursor()

        try:
            mycursor.execute(sql_query)
            myresults =mycursor.fetchall()
            for row in myresults:
                for x in row:
                    mypassword_queue.append(x)
        except:
            print('error occured')

        if (username and password) in mypassword_queue:
            print('there is something')
        else:
            print('there is no anything')

        self.con.close()


root = connections()
#---you must have created a database with choice of your database name for this case it is testing
#---- the data inside has name as tumusiime and password 1234
root.connect_database('tumusiime','1234')

Answer 2

我会给你一个代码，它适用于所有使用 mysql.connector 的查询

**config= {'user': your_user',
'password': 'your_pass',
'host': 'ip_of_your_db',
'database': 'name_of_your_db',
'raise_on_warnings': True}


def run_query(self,query):    
    try:
        conn = mysql.connector.connect(**self._config)
        if conn.is_connected():
            print('run_query: Connecting MySql Db')
        cur = conn.cursor()
        cur.execute(query)
        r= cur.fetchall()
        return r
    except mysql.connector.Error as err:
        if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
            print("run_query: Error in username or password")
        elif err.errno == errorcode.ER_BAD_DB_ERROR:
            print("run_query: Dabatase doesn't exist")
        else:
            print(err)
    finally:
        conn.commit()
        conn.close()

每个查询都需要有这种格式

query='SELECT * FROM {}'.format("your_db.your_table")
answer=self.run_query(query)