KINGBASE语句

SELECT
   A.table_name "表名",
   C.COMMENTS "表注释",
   concat(C.COMMENTS,'(',A.table_name,')') "拼接字段",
   A.column_name "字段名",
   D.COMMENTS "字段注释",
   upper(A.data_type) "字段类型",
   coalesce(A.character_maximum_length, A.numeric_precision, -1) as "长度"，
   D.COMMENTS "备注"
FROM
   information_schema.columns A 
LEFT JOIN (
    SELECT
        sys_attribute.attname,
        sys_class.oid
    FROM
        sys_index,
        sys_class,
        sys_attribute
    WHERE sys_index.indrelid = sys_class.oid
    AND sys_attribute.attrelid = sys_class.oid
    AND sys_attribute.attnum = ANY (sys_index.indkey)
) B ON B.oid = A.table_name :: regclass AND A.column_name = b.attname
LEFT JOIN (SELECT TABLE_NAME,COMMENTS from all_tab_comments WHERE OWNER = '模式名称') C ON A.table_name = C.table_name
LEFT JOIN user_col_comments D ON A.table_name = D.table_name AND A.column_name = D.column_name
WHERE
   A.table_schema = '模式名称'
ORDER BY
   A.table_name,ordinal_position ASC

MySQL语句

SELECT
	c.table_name 表名,
	t.TABLE_COMMENT 表注释,
	CONCAT(t.TABLE_COMMENT,'(',c.table_name,')') 拼接字段,
	c.COLUMN_NAME 字段名,
	c.COLUMN_COMMENT 字段注释,
	UPPER(c.DATA_TYPE) 字段类型,
	COALESCE(character_maximum_length, numeric_precision, -1) 长度,
	c.COLUMN_COMMENT 备注
FROM
	information_schema.COLUMNS c,
	information_schema.TABLES t 
WHERE
	c.TABLE_SCHEMA = '数据库名称' 
	AND c.TABLE_SCHEMA = t.TABLE_SCHEMA 
	AND c.TABLE_NAME = t.TABLE_NAME 
ORDER BY
	c.table_name ASC,
	c.COLUMN_NAME ASC;

后续会根据需求逐渐补充。