转自 ：http://gis-conquer.blog.sohu.com/170243422.html
查询所有表名：
select t.table_name from user_tables t;
查询所有字段名：
select t.column_name from user_col_comments t;
查询指定表的所有字段名：
select t.column_name from user_col_comments t where t.table_name = 'BIZ_DICT_XB';
查询指定表的所有字段名和字段说明：
select t.column_name, t.column_name from user_col_comments t where t.table_name = 'BIZ_DICT_XB';
查询所有表的表名和表说明：
select t.table_name,f.comments from user_tables t inner join user_tab_comments f on t.table_name = f.table_name;
补充：
//效率较高
select o.name AS NAME,
nvl(c.comment$,' ') AS DESCRIPT
from sys.obj$ o
left join sys.com$ c on c.obj#=o.obj# and c.col# is null
where o.owner# = userenv('SCHEMAID')
and o.type# = 2
and not exists (select 1 from sys.recyclebin$ r where r.obj# = o.obj#)
查询模糊表名的表名和表说明：
select t.table_name from user_tables t where t.table_name like 'BIZ_DICT%';
select t.table_name,f.comments from user_tables t inner join user_tab_comments f on t.table_name = f.table_name where t.table_name like 'BIZ_DICT%';