def close(self):
		'''关闭与数据库的连接'''
		if VERBOSE:
			print 'Database connection CLOSE.'
		self.conn.close()
def tag(self, g):
        self.g = g
        self.g.beginPath()
        self.g.fillText("%d, %d"%(self.x, self.y),self.x, self.y)
        self.g.stroke()