SELECT
	t.TABLE_NAME AS 表名,
	t.COLUMN_NAME AS 字段名,
	t.COLUMN_TYPE AS 数据类型,
CASE
		IFNULL( t.COLUMN_DEFAULT, 'Null' ) 
		WHEN '' THEN
		'空字符串' 
		WHEN 'Null' THEN
		'NULL' ELSE t.COLUMN_DEFAULT 
	END AS 默认值,
CASE
		t.IS_NULLABLE 
		WHEN 'YES' THEN
		'是' ELSE '否' 
	END AS 是否允许为空,
	t.COLUMN_COMMENT AS 字段说明 
FROM
	information_schema.COLUMNS t 
WHERE
	t.TABLE_SCHEMA = '这里填写库名';