database.py

#database.py 
#use python 3.4 
import sys, shelve
def store_person(db):
	"""
	Query user for data and store it in the shelf object
	"""
	pid = input('Enter unique ID number: ')
	person = {}
	person['name'] = input('Enter name: ')
	person['age'] = input('Enter age: ')
	person['phone'] = input('Enter phone number: ')

	db[pid] = person

def lookup_person(db):
	"""
	Query user for ID and desired field, and fetch the corresponding data from the shelf object
	"""

	pid = input('Enter ID number: ')
	field = input('What would you like to konw? (name, age, phone) ')
	field = field.strip().lower()
	field = field.split(',')
	for ele in field:
		try:
			print(ele)
			print(ele.capitalize()+':'+db[pid][ele])
		except KeyError:
			continue

def print_help():
	print('The available commands are: ')
	print('store  : Stores information about a person')
	print('lookup : Look up a person from ID number')
	print('quit   : Save changes and exit')
	print('?      : Prints this message')

def enter_command():
	cmd = input('Enter command (? for help): ')
	cmd = cmd.strip().lower()
	return cmd

def main():
	database = shelve.open('database.dat')
	try:
		while True:
			cmd =enter_command()
			if cmd == 'store':
				store_person(database)
			elif cmd == 'lookup':
				lookup_person(database)
			elif cmd == '?':
				print_help()
			elif cmd == 'quit':
				return
	finally:
		database.close()
if __name__ =='__main__': main()