text: col HOST_NAME format a20
  col STARTUP_TIME format a20
  col INSTANCE_NAME format a15
  set linesize 120
  
  alter session set nls_date_format = 'DD-MON-YY hh24:mi:ss';
  
  SELECT INSTANCE_NAME, INSTANCE_NUMBER, HOST_NAME , STARTUP_TIME, STATUS FROM  GV$INSTANCE;
  