学の夢的专栏

命令输入：Create  tablespace tbs_nsoft_exams datafile ‘E:\database\exams.dbf’（表空间存储盘符） size 10m autoextend on next 2m maxsize unlimited

select a.table_name as 表名,user_tab_comments.comments as 表名备注,a.column_name as 列名,   a.data_type as 类型,   decode(a.data_type, 'NUMBER', a.data_precision, a.data_length) as 长度, a.data_scale as 小数位数,