修改sqlplus的环境，让操作更方便

vi $ORACLE_HOME/sqlplus/admin/glogin.sql

define _editor=vi
set serveroutput on size 1000000
set trimspool on
set long 5000
set linesize 100
set pagesize 9999
column plan_plus_exp format a80
column global_name new_value gname
set termout off
define gname=idle
column global_name new_value gname
select lower(user) || '@' || substr( global_name, 1, decode( dot, 0, length(global_name),dot-1) ) global_name
from (select global_name, instr(global_name,'.') dot from global_name );
set sqlprompt '&gname> '
set termout on