python简单模拟数据库程序

#database.py

import sys,shelve

def store_person(db):
"""
Query user for data and store it in the shelf object
"""
pid = raw_input("Enter unique ID number:")
person = {}
person['name'] = raw_input("Enter name: ")
person['age']  = raw_input("Enter age: ")
person['phone']= raw_input("Enter phone")
db[pid] = person

def lookup_person(db):
"""
Query user for ID
"""
pid = raw_input("Enter ID number:")
field = raw_input("what would you like to know ? name,age,phont")
field = field.strip().lower()
print field.capitalize() + ':',db[pid][field]

def print_help():
print "the available commands are:"
print "store : store informantion about a person"
print "lookup: look up a person fron ID number"
print "quit  : Save changes and exit"
print "?     : Prints this message"

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

def main():
database = shelve.open('/home/weichong/database.txt')
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()