Why is name 'sqlite3' is not defined error?

Question

Python

db.py file created

import sqlite3
from sqlite3 import Error
import os

conn = sqlite3.connect('baza1.db')
cur = conn.cursor()
cur.execute('CREATE TABLE IF NOT EXISTS baza1(user_id INTEGER, username TEXT, mail TEXT)')
conn.commit()

in main
import db,

when I start the bot, I get the error
name 'sqlite3' is not defined

, yet the code for execution:

@dp.message_handler(content_types=['text'])
async def get_message(message):
   if message.text == "Сценарий1":  # нажав сценарий мы должны получить поле для ввода емейл
       await message.answer("Введите электронную почту. Она требуется для корректной работы с вами далее", reply_markup=ReplyKeyboardRemove())
       await NewPost.next()
@dp.message_handler(state=NewPost.email)
async def isValid(message: types.Message, state: FSMContext):
           email = message.text

           await state.update_data(
               {'email': email}
           )

           regex = re.compile(r'([A-Za-z0-9]+[.-_])*[A-Za-z0-9][email protected][A-Za-z0-9-]+(\.[A-Z|a-z]{2,})+')

           if re.fullmatch(regex, email):
               print("Valid email")

           #await message.reply('Привет, я эхо-бот, напиши мне что-нибудь!')
           try:
                   conn = sqlite3.connect('baza1.db')
                   cur = conn.cursor()
                   cur.execute('CREATE TABLE IF NOT EXISTS baza1(user_id INTEGER, username TEXT, mail TEXT)')
                   conn.commit()
           except Exception as e:
                   print(e)
                   conn = sqlite3.connect('baza1.db')
                   cur = conn.cursor()
                   cur.execute('CREATE TABLE IF NOT EXISTS baza1(user_id INTEGER, username TEXT, mail TEXT)')
                   conn.commit()

Error in console:

File "G:\PYTHON\pythonProject123\main.py", line 103, in isValid
    conn = sqlite3.connect('baza1.db')
NameError: name 'sqlite3' is not defined
Valid email
name 'sqlite3' is not defined

They write that in Python itself there may be a jamb in the module.
Like it needs to be rebuilt somehow ...

and here the question

is the PANDAS module,

can it be better?

Answer 1

1. Imports don't work that way. All modules must be included directly in each file in which it is called (plus explicit is better than implicit ) - i.e. if the sqlite module is needed in main.py , then you need to import it in main.py , regardless of whether it is included in db.py or not.
2. Which is better, a fork or a mug? (In other words, sqlite and pandas do different things)
----
3. What is the point of db.py if the code from it is duplicated in main?