获取表字段：

select * 
from user_tab_columns 
where Table_Name='用户表' 
order by column_name

获取表注释：

select * 
from user_tab_comments 
where Table_Name='用户表'

order by Table_Name

获取字段注释：

select * 
from user_col_comments 
where Table_Name='用户表'

order by column_name

/* 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='zfxfzb'

/* 
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

相应的还有dba_col_comments，all_col_comments，这两个比user_col_comments多了ower列。 
*/