获取oracle表结构的字段信息

select a.column_id as 列号, 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,

decode(e.uniqueness,'UNIQUE','Y','N') as 是否是唯一的, decode(e.key,'Y','Y','N') 是否是主键,

f.comments as 注释, a.nullable as 是否允许空, a.data_default as 默认值

from user_tab_columns a, user_col_comments f,

(select b.table_name, b.index_name,b.uniqueness, c.column_name,

decode(d.constraint_name,NULL,'N','Y') key

from user_indexes b, user_ind_columns c,

( select constraint_name from user_constraints where constraint_type='P' ) d

where b.index_name=c.index_name and b.index_name=d.constraint_name(+) ) e

where a.table_name='TEMPTABLE' and a.table_name=e.table_name(+) and a.column_name=e.column_name(+)

and a.table_name=f.table_name and a.column_name=f.column_name

order by a.column_id

select TC.table_name , TC.column_name ,TC.DATA_TYPE,TC.data_length,TC.data_precision,TC.nullable,

TC.char_col_decl_length,

decode(C.constraint_type,'P','PK','U','Unique','R','FK','C','Check',C.constraint_type)

from USER_TAB_COLUMNS TC,USER_CONS_COLUMNS CC ,user_constraints C

where TC.table_name = 'EMP'

and TC.table_name = CC.table_name(+)

and TC.column_name = CC.column_name (+)

and CC.constraint_name = C.constraint_name(+)

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 from  user_tab_columns A,user_col_comments B where a.COLUMN_NAME=b.column_name and    A.Table_Name = B.Table_Name and A.Table_Name='TEST'

获取表：

select table_name from user_tables; //当前用户的表

select table_name from all_tables; //所有用户的表

select table_name from dba_tables; //包括系统表

select table_name from dba_tables where owner='用户名'

user_tables：

table_name,tablespace_name,last_analyzed等

dba_tables：

ower,table_name,tablespace_name,last_analyzed等

all_tables：

ower,table_name,tablespace_name,last_analyzed等

all_objects：

ower,object_name,subobject_name,object_id,created,last_ddl_time,timestamp,status等

获取表字段：

select * from user_tab_columns where Table_Name='用户表';

select * from all_tab_columns where Table_Name='用户表';

select * from dba_tab_columns where Table_Name='用户表';

user_tab_columns：

table_name,column_name,data_type,data_length,data_precision,data_scale,nullable,column_id等

all_tab_columns ：

ower,table_name,column_name,data_type,data_length,data_precision,data_scale,nullable,column_id等

dba_tab_columns：

ower,table_name,column_name,data_type,data_length,data_precision,data_scale,nullable,column_id等

获取表注释：

select * from user_tab_comments

user_tab_comments：table_name,table_type,comments

--相应的还有dba_tab_comments，all_tab_comments，这两个比user_tab_comments多了ower列。

获取字段注释：

select * from user_col_comments

user_col_comments：table_name,column_name,comments