SQLite NameError：名称“光标”未定义

Question

I am trying to make a virtual machine, but in a CLI. I am using SQLite for the login data and potentially for other data in the future. Sadly, I keep getting this error and I don't know how to fix it. Could you guys help me? I plan on releasing the first version of this on GitHub when I fixed this error.

from os import system, name
import sqlite3
from sqlite3 import Error

db_file = "userdata"

def create_connection(db_file):
    """ create a database connection to a SQLite database """
    conn = None
    try:
        conn = sqlite3.connect(db_file)
        print(sqlite3.version)
    except Error as e:
        print(e)
    finally:
        if conn:
            conn.close()

def clear():
    if name == 'nt':
        _ = system('cls')
    else: _ = system('clear')

def todolist():
    print("     Backlog | To-do                     | In progress     | Finished (coming in next update)")
    print("     --------|---------------------------|-----------------|---------------------------------")
    print("     -       | Register function         | SQLite database | Basis build")
    print("             | Forgot password function  |                 |")
    print("             | Login function            |                 |")

print("Made by The Celt")

print("Welcome back!")
print("Login (l)")
print("Register (r)")
print("Forgot password (fp)")

starterAction = input("What do you want to do? ")

create_connection(db_file)

if starterAction == "l":
    s.sleep(0.8)
    clear()
    insertUsername = input("Username:")
    for name in ('bar','foo'): 
        cursor.execute("SELECT rowid FROM components WHERE name = %s"%insertUsername, (name,))
        data=cursor.fetchone()
    if data is None:
        print("Could not find this username in the database!")
    else:
        insertPassword = input("Password: ")
        for name in ('bar','foo'): 
            cursor.execute("SELECT rowid FROM components WHERE name = %s"%insertPassword, (name,))
            data=cursor.fetchone()
        if data is None:
            print("Could not find this password in the database!")
        else:
            print("Welcome back, %s"%insertUsername)

elif starterAction == "r":
    s.sleep(0.8)
    clear()
    print("Still in progress!")
elif starterAction == "todolist":
    todolist()

Answer 1

It is not a sqlite error, it is a python error: You did not defined "cursor"

You have to define conn and the cursor within the global scope, near to db_file

db_file = "userdata"
conn = None
cursor = None

and then, after connection has been established (within create_connection routine), you need to add cursor creation

conn = sqlite3.connect(db_file)
cursor = conn.cursor()    

see here for details

And the way you're selecting from db is also wrong:

for security's sake use bind variables where possible, like that (from documentaion)

cur.execute('SELECT * FROM stocks WHERE symbol=?', t)  

if you still insist on concatenating the query string (which I NOT recommend) you need to place value you're searching for within two apostrophes (I've updated %s to '%s')

... WHERE name = '%s'"%insertPassword, (name,) ...