描述函数Describe Function

DESCRIBE FUNCTION [EXTENDED] [db_name.]function_name

返回现有函数(实现类和用法)的元数据。Return the metadata of an existing function (implementing class and usage). 如果该函数不存在,则会引发异常。If the function does not exist, an exception is thrown.

EXTENDED

显示扩展的用法信息。Show extended usage information.