def close(self):
		'''关闭与数据库的连接'''
		if VERBOSE:
			print 'Database connection CLOSE.'
		self.conn.close()
def add_dimension(cls, dataset, dimension, dim_pos, values, vdim):
        data = dataset.data.copy()
        if dimension.name not in data:
            data[dimension.name] = values
        return data