contacts.py

import os
import sqlite3

def create_tables(conn):
    conn.execute("CREATE TABLE contacts (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, email TEXT)")
    conn.commit()

def connect(path="contacts.db", syncdb=False):
    """
    Connects to the database and ensures there are tables.
    """
    if not os.path.exists(path):
        syncdb=True

    conn = sqlite3.connect(path)
    if syncdb:
        create_tables(conn)
    
    return conn

def insert(name, email, conn=None):
    if not conn: conn = connect()

    sql = "INSERT INTO contacts (name, email) VALUES  (?, ?)"
    conn.execute(sql, (name, email))
    conn.commit()

if __name__ == "__main__":
    name  = raw_input("Enter name: ")
    email = raw_input("Enter email: ")
    conn  = connect()
    insert(name, email, conn)

    contacts = conn.execute("SELECT count(id) FROM contacts").fetchone()[0]
    print "There are now %i contacts" % contacts

    conn.close()

contacts_mongo.py

from pymongo import MongoClient
from datetime import datetime

def connect(database="contacts", host="localhost", port=27017):
    """
    Connects to the database 
    """
    client = MongoClient(host, port)
    return client[database]

if __name__ == "__main__":
    entry = {
        "name": raw_input("Enter name: "),
        "email": raw_input("Enter email: "),
        "created": datetime.now()
    }

    while True:
        key = raw_input("Add key: ")
        if not key: break
        val = raw_input("Add val: ")
        if not val: break
        entry[key] = val

    db = connect()
    collection = db.contacts

    collection.insert(entry)
    print "There are now %i documents in contacts" % collection.count()

contacts_pg.py

"""
Database already created:

CREATE TABLE contacts (
	id SERIAL NOT NULL,
	name VARCHAR(50) NOT NULL,
	email VARCHAR(50) NOT NULL,
CONSTRAINT contacts_pkey PRIMARY KEY (id));
"""


import os
import psycopg2

def connect(db, user, password, host="localhost", port=5432):
    """
    Connects to the database and ensures there are tables.
    """
    conn = psycopg2.connect(**{
        "database": db,
        "user": user,
        "password": password,
        "host": host,
        "port": port

    })
    return conn

def insert(name, email, conn=None):
    if not conn: conn = connect()
    
    cursor = conn.cursor()
    sql = "INSERT INTO contacts (name, email) VALUES  (%s, %s)"
    cursor.execute(sql, (name, email))
    conn.commit()

if __name__ == "__main__":
    name  = raw_input("Enter name: ")
    email = raw_input("Enter email: ")
    conn  = connect("contacts", "example", "password")
    insert(name, email, conn)

    cursor = conn.cursor()
    cursor.execute("SELECT count(id) FROM contacts")
    contacts = cursor.fetchone()[0]
    print "There are now %i contacts" % contacts

    conn.close()