1.UID

返回标识当前用户的唯一整数

SQL> show user

USER 为"GAO"

SQL> select username,user_id from dba_users where user_id=uid;

USERNAME                         USER_ID

------------------------------ ---------

GAO                                   25

2.USER

返回当前用户的名字

SQL> select user from dual;

USER

------------------------------

GAO

 

3.ESCAPE

 escape关键字经常用于使某些特殊字符，如通配符：'%','_'转义为它们原来的字符的意义，被定义的转义字符通常使用'\',但是也可以使用其他的符号。

eg:

视图

create or replace VIEW view1 as

select 'yaobo' as vname from dual

union all

select 'bxxx' as vname from dual

union all

select 'xyz' as vname from dual

union all

select '_%xxx_' as vname from dual

union all

select '_\xx' as vname from dual;

select * from view1 where vname like '_\\xx%' escape '\';  --将‘\'转义成字符

select * from view1 where vname like '\_%xx%' escape '\';  --将‘_'转义成字符，在sql中（'_'代表任意单个字符）