Example pyTelegramBotAPI with SQLite3 #1

example_bot.py

import sqlite3
import telebot 

TOKEN = "<YOUR BOT TOKEN>"
bot = telebot.TeleBot(TOKEN)


# I suggest you to download SQLite Studio for creating database and tables...
conn = sqlite3.connect('database.db', check_same_thread=False) # Connecting to the database
cursor = conn.cursor()

# For add someone in the database 
def db_table_val(user_id: int, user_name: str):
    cursor.execute('INSERT INTO user_data (user_id, user_name) VALUES (?, ?)',
                   (user_id, user_name))
    conn.commit()

    
@bot.message_handler(commands=['start'])
def send_welcome(message):
    us_id = message.chat.id # Telegram ID of the user
    us_name = message.chat.first_name # Username of the user


    if message.chat.type == 'private':
        try:
            cursor.execute(f"SELECT user_id from user_data WHERE user_id = {us_id}") # First check if user is in the database
            records = cursor.fetchone()
            
            bot.send_message(message.chat.id, f""
                                          f"Hello, Welcome Back you're in our database\n"
                                          )
        except: # If user is not in the database...
            db_table_val(user_id=us_id, user_name=us_name) # .... This will add it...
            bot.send_message(message.chat.id, f"Welcome new user"
                                              )

Thank you very much