Python Music Quiz (Sqlite3 Error)

import csv
import sqlite3
from random import choice

connection = sqlite3.connect('users.db')

cursor = connection.cursor()


def welcome():
    print("#####################################")
    print("#  .::Welcome to The Music Quiz::.  #")
    print("#           .:Version 1:.           #")
    print("#####################################")
    print("")

    option = input('Do you want to login or register? ')
    option = option.lower()

    if option == 'login':
        login()
    elif option == 'register':
        register()
    else:
        print('Enter login or register')


def register():

    sql = '''CREATE TABLE IF NOT EXISTS Players
                    (PID INTEGER PRIMARY KEY AUTOINCREMENT,
                     USERNAME VARCHAR(100),
                     PASSWORD VARCHAR(100),
                     SCORE INT)'''
    cursor.execute(sql)

    print('Follow the register instructions')

    username_check = False

    while username_check == False:

        tempusername = input('Please enter a Username: ')

        cursor.execute('''SELECT username FROM Players WHERE username=?''', (tempusername,))
        exists = cursor.fetchall()

        if not exists:
            username_check = True
        else:
            print('Username not available, try again.')
            username_check = False

    if username_check == True:

        password_check = False

        while password_check == False:
            temppassword = input('Please enter a Password: ')

            tempscore = "0"

            params = (tempusername, temppassword, tempscore)

            cursor.execute("INSERT INTO Players VALUES (NULL, ?, ?, ?)", params)
            cursor.execute(sql)

            connection.commit()

            print("Thank You for Registering, You can now login")
            print("")
            login()


def login():
    logged_in = False

    while logged_in == False:
        username = input('Please enter your Username ')
        password = input('Please enter your Password ')

        cursor.execute('SELECT * from Players WHERE username="%s" AND password="%s"' % (username, password))

        if cursor.fetchone() is not None:
            logged_in = True
            print('Logged in successfully as ' + username)
            print("")

            cursor.execute('SELECT score from Players WHERE username="%s"' % (username))
            currentScore = cursor.fetchall()
            currentScore = [x[0] for x in currentScore]

            song_list = ''
            song_name = ''
            artist_name = ''
            song_letters = ''
            chances = 2
            score = 0
            quiz = True

            with open('songs.csv', 'rt') as f:
                reader = csv.reader(f)
                song_list = list(reader)

                print("Your Highest Score is " + str(currentScore))
                print("Can you beat it?")
                print("")

                while quiz == True:
                    if chances == 2:
                        Song = (choice(song_list))
                        Song = str(Song)
                        Song.split(",")
                        artist_name, song_name = Song.split(",")

                    for char in "']":
                        song_name = song_name.replace(char, '')

                    for char in "['":
                        artist_name = artist_name.replace(char, '')

                    song_name.lower()

                    print("You Have " + str(chances), "chances remaining!")
                    print("The Artist of the song is " + artist_name)

                    words = song_name.split()
                    song_letters = [word[0] for word in words]

                    print("The first letter of each word in the song name are " + str(song_letters))
                    guess = input("What is the name of the song? ")
                    guess = guess.lower()

                    if guess == song_name:
                        print("Correct the Song was " + song_name, "by " + artist_name)
                        score = score + 3
                        print("")
                        print("You scored 3 points for guessing the song the first try")

                    else:
                        print("That is incorrect, Try again")
                        print("You have 1 chance left!")
                        chances = chances - 1

                        guess = input("What is the name of the song? ")
                        guess = guess.lower()

                        if guess == song_name:
                            print("Correct the Song was " + song_name, "by " + artist_name)
                            score = score + 1
                            print("")
                            print("You scored 1 point for guessing the song the second try")
                            chances = 0
                            chances = 2

                        else:
                            print("")
                            print("You have run out of lives!")
                            print("You Scored " + str(score), "points")

                            if str((score)) > str((currentScore)):
                                currentscore = score

                                cursor.execute('''UPDATE Players SET score = ? WHERE username =?''', (username, score))
                                connection.commit()
                                connection.close()

                            quiz = False

        else:
            logged_in = False
            print('One or more details are incorrect, Try Again')


welcome()