This is a python login system with the database(MySql). In this project I have used the Tkinter module for the GUI of the project. Before run this on your system you make sure you have a mysql database on your system, if not then install and then create the table named as "login" and column name will be "user" and "password" and now you good to go.

LogInSystem.py

from tkinter import *
from tkinter import messagebox
import mysql.connector
import os
import time

#connecting to the database
db = mysql.connector.connect(host="localhost",user="root",passwd="root",database="techienaman")
mycur = db.cursor()

def error_destroy():
    err.destroy()

def succ_destroy():
    succ.destroy()
    root1.destroy()

def error():
    global err
    err = Toplevel(root1)
    err.title("Error")
    err.geometry("200x100")
    Label(err,text="All fields are required..",fg="red",font="bold").pack()
    Label(err,text="").pack()
    Button(err,text="Ok",bg="grey",width=8,height=1,command=error_destroy).pack()

def success():
    global succ
    succ = Toplevel(root1)
    succ.title("Success")
    succ.geometry("200x100")
    Label(succ, text="Registration successful...", fg="green", font="bold").pack()
    Label(succ, text="").pack()
    Button(succ, text="Ok", bg="grey", width=8, height=1, command=succ_destroy).pack()

def register_user():
    username_info = username.get()
    password_info = password.get()
    if username_info == "":
        error()
    elif password_info == "":
        error()
    else:
        sql = "insert into login values(%s,%s)"
        t = (username_info, password_info)
        mycur.execute(sql, t)
        db.commit()
        Label(root1, text="").pack()
        time.sleep(0.50)
        success()



def registration():
    global root1
    root1 = Toplevel(root)
    root1.title("Registration Portal")
    root1.geometry("300x250")
    global username
    global password
    Label(root1,text="Register your account",bg="grey",fg="black",font="bold",width=300).pack()
    username = StringVar()
    password = StringVar()
    Label(root1,text="").pack()
    Label(root1,text="Username :",font="bold").pack()
    Entry(root1,textvariable=username).pack()
    Label(root1, text="").pack()
    Label(root1, text="Password :").pack()
    Entry(root1, textvariable=password,show="*").pack()
    Label(root1, text="").pack()
    Button(root1,text="Register",bg="red",command=register_user).pack()

def login():
    global root2
    root2 = Toplevel(root)
    root2.title("Log-In Portal")
    root2.geometry("300x300")
    global username_varify
    global password_varify
    Label(root2, text="Log-In Portal", bg="grey", fg="black", font="bold",width=300).pack()
    username_varify = StringVar()
    password_varify = StringVar()
    Label(root2, text="").pack()
    Label(root2, text="Username :", font="bold").pack()
    Entry(root2, textvariable=username_varify).pack()
    Label(root2, text="").pack()
    Label(root2, text="Password :").pack()
    Entry(root2, textvariable=password_varify, show="*").pack()
    Label(root2, text="").pack()
    Button(root2, text="Log-In", bg="red",command=login_varify).pack()
    Label(root2, text="")

def logg_destroy():
    logg.destroy()
    root2.destroy()

def fail_destroy():
    fail.destroy()

def logged():
    global logg
    logg = Toplevel(root2)
    logg.title("Welcome")
    logg.geometry("200x100")
    Label(logg, text="Welcome {} ".format(username_varify.get()), fg="green", font="bold").pack()
    Label(logg, text="").pack()
    Button(logg, text="Log-Out", bg="grey", width=8, height=1, command=logg_destroy).pack()


def failed():
    global fail
    fail = Toplevel(root2)
    fail.title("Invalid")
    fail.geometry("200x100")
    Label(fail, text="Invalid credentials...", fg="red", font="bold").pack()
    Label(fail, text="").pack()
    Button(fail, text="Ok", bg="grey", width=8, height=1, command=fail_destroy).pack()


def login_varify():
    user_varify = username_varify.get()
    pas_varify = password_varify.get()
    sql = "select * from login where user = %s and password = %s"
    mycur.execute(sql,[(user_varify),(pas_varify)])
    results = mycur.fetchall()
    if results:
        for i in results:
            logged()
            break
    else:
        failed()


def main_screen():
    global root
    root = Tk()
    root.title("Log-IN Portal")
    root.geometry("300x300")
    Label(root,text="Welcome to Log-In Protal",font="bold",bg="grey",fg="black",width=300).pack()
    Label(root,text="").pack()
    Button(root,text="Log-IN",width="8",height="1",bg="red",font="bold",command=login).pack()
    Label(root,text="").pack()
    Button(root, text="Registration",height="1",width="15",bg="red",font="bold",command=registration).pack()
    Label(root,text="").pack()
    Label(root,text="").pack()
    Label(root,text="Developed By Naman Kumar").pack()

main_screen()
root.mainloop()