def insertDomain(self, domain, indegree=0, outdegree=0):
		'''增加一个域名'''
		cur = self.conn.cursor()
		cur.execute("INSERT INTO Domains VALUES (NULL,?,?,?)", (domain, indegree, outdegree))
		# 写入到文件中
		self.conn.commit()
def connect ():
    '''
    Create the connection to the MongoDB and create 3 collections needed
    '''
    try:
        # Create the connection to the local host 
        conn = pymongo.MongoClient()
        print 'MongoDB Connection Successful'
    except pymongo.errors.ConnectionFailure, err:
        print 'MongoDB Connection Unsuccessful'
        return False