SQLite3从数据库读取用户名和密码

Question

I am attempting to use a database to read valid Logins from. One column is Username the other is Password. How do i write my code so that IF the Username entry from the user and the password entry from the user match a row within the database it will validate the log in and move onto the next page which is this example is called "Screen"

I have made a demo login page below in which i have added a creating database function. What must i edit/add to for fill what my aim is.

from tkinter import * #imports all the GUI libraries
from tkinter import messagebox #so it can be used outside idle
from tkinter import ttk
import sqlite3

class LoginPopup():
    #constructor sets up the buttons
    def __init__(Top):
        Top.GenericGui = Tk()#creating a window
        Top.GenericGui.title('Login')
        Top.GenericGui.geometry('300x200+250+30')
        Top.Check = 1
        Top.GenericGui.iconbitmap('home.ico')
        Password = StringVar()
        Username = StringVar()
        conn = sqlite3.connect('Logins.db')
        c = conn.cursor()

    #takes you back to the main menu
    def BackToMain():
        Top.delete()
        openscreen = Screen()


    def create_table():
        c.execute("CREATE TABLE IF NOT EXISTS stuffToPlot(Username TEXT, Password TEXT)")

    def read_from_db():
        c.execute('SELECT * FROM stuffToPlot')
        data = c.fetchone()
        for row in data:
            print(row)

    def UsernameAndPassword(Top):
        UsernameAttempt = Username.get()#how to get value from entry box
        PasswordAttempt = Password.get()#how to get value from entry box

    #Login Components
    LoginVerify = ttk.Button(Top.GenericGui, text="Login", command = lambda: UsernameAndPassword(Top)).place(x=220,y=170)
    ttk.Entry(Top.GenericGui,textvariable = Username,width = 20).place(x=140,y=60)
    ttk.Entry(Top.GenericGui,show = '*',textvariable = Password,width = 20).place(x=140,y=100)#can hide letters entered with *
    ttk.Label(Top.GenericGui,text = 'Username:').place(x=40,y=60)
    ttk.Label(Top.GenericGui,text = 'Password:').place(x=40,y=100)
    Label(Top.GenericGui,text = '  Please Enter Your Username \nand Password ',font = ('TkDefaultFont',12)).pack(side = TOP, fill = X)


    create_table()    
    read_from_db()
    c.close
    conn.close()

class Screen(LoginPopup):

    #constructor sets up the buttons
    def __init__(Top):
        Top.GenericGui = Tk()#creating a window
        Top.GenericGui.title('Screen')
        Top.GenericGui.geometry('300x200+250+30')
        Top.Check = 1
        Top.GenericGui.iconbitmap('home.ico')
        Password = StringVar()
        Username = StringVar()

runprogram = LoginPopup()

Thanks for taking your time to read and any assistance would be appreciated

Answer 1

Write a generic SQL query to get all matching rows:

sql = "SELECT * FROM StuffToPlot WHERE Username = ? and Password = ?"

Then execute the query, filling in the specific values for username and password:

c.execute(sql, (UsernameAttempt, PasswordAttempt))

If you get no results from this query, then the username and/or password did not match.

If you get exactly one result, then they matched.

If you get more than one result, then something has gone terribly wrong.