select
a.column_name 字段名,a.data_type 数据类型,
a.data_length 长度,a.data_precision 整数位,
a.data_scale 小数位,a.nullable 允许空值,
a.data_default 缺省值,b.comments 备注,
c.indexcount 索引次数
from
user_tab_columns a,
user_col_comments b,
(select count(*) indexcount,column_name 
from user_ind_columns where 
table_name = 'table_test' group by column_name) c
where
a.table_name = b.table_name
and a.column_name = b.column_name
and a.column_name = c.column_name(+)
and a.table_name = 'table_name'