SELECT  
  c.table_schema 数据库名称,
	c.TABLE_NAME 表名,
	t.TABLE_COMMENT,
  c.COLUMN_NAME 列名,   
  c.DATA_TYPE 列字段类型,   
	c.CHARACTER_MAXIMUM_LENGTH 列长度,
  c.IS_NULLABLE 列是否为空,  
  c.COLUMN_DEFAULT 列默认值,  
  c.COLUMN_COMMENT 列备注   
FROM  
 INFORMATION_SCHEMA.COLUMNS as c
left join information_schema.TABLES as t on t.TABLE_NAME = c.TABLE_NAME
where  
-- 数据库名称
t.table_schema ='test_db' 
and 
-- 数据库名称
c.table_schema ='test_db'  
and
-- 数据库表名
c.TABLE_NAME = 'edm_task'