step 3 in http://flask.pocoo.org/docs/tutorial/dbinit/#tutorial-dbinit

flaskr.py

#all the imports
from __future__ import with_statement
from contextlib import closing
import sqlite3
from flask import Flask, request, session, g, redirect, url_for, abort, render_template, flash

# configuration
DATABASE = "/tmp/flaskr.db"
DEBUG = True
SECRET_KEY = 'development key'
USERNAME = 'admin'
PASSWORD = 'default'

# create our little application
app = Flask(__name__)
app.config.from_envvar('FLASKR_SETTINGS', silent=True)

def connect_db():
    return sqlite3.connect(app.config['DATABASE'])

def init_db():
    with closing(connect_db()) as db:
        with app.open_resource('schema.sql') as f:
            db.cursor().executescript(f.read())
        db.commit()

if __name__ == '__main__':
    app.run()