Configure your sql prompt

To configure add the below lines to glogin.sql file in $ORACLE_HOME/sqlplus/admin

column mydbname new_value mydbname noprint
select user ||'@' || name "mydbname" from v$database ;
set sqlprompt "&&mydbname SQL> "
--
set termout on feedback on heading on pagesize 5000 time on timing on
set serveroutput on size 100000
define_editor=vi