def close(self):
		'''关闭与数据库的连接'''
		if VERBOSE:
			print 'Database connection CLOSE.'
		self.conn.close()
def f(i):
        start = W[i]
        extent = W[i + 1] - W[i]
        rv = te.reduce_axis((0, extent))
        return te.sum(X[rv + start], axis=rv)