Change SQLPlus color according to database name

I am in and out of lots of databases every day. I wanted a way to color code my session so that I could tell at a glance if I was logged on to production or non-production. So  I added this to my login.sql file:

 

set termout off
set timing off
COLUMN  host_cmd_col  NEW_VALUE host_cmd

SELECT  ( CASE 
          when sys_context('USERENV', 'DB_NAME')
          in (  'PROD', 'IPROD', 'KPROD',     -- rac instances
                'PA', 'PALP', 'PP2', 'BPROD', -- db server 1
                'ERP', 'QPROD', 'PR4',        -- db2 server
                'HR', 'HTA'                   -- db3 server
             )
  THEN 'COLOR 0E'
  else 'COLOR 70'
        END) host_cmd_col
FROM dual;

HOST  &host_cmd

/*
COLOR [attr]

attr        Specifies color attribute of console output

Color attributes are specified by TWO hex digits -- the first corresponds to the
background; the second the foreground. Each digit can be any of the below values.

0 = Black    8 = Gray
1 = Blue     9 = Light Blue
2 = Green    A = Light Green
3 = Aqua     B = Light Aqua
4 = Red      C = Light Red
5 = Purple   D = Light Purple
6 = Yellow   E = Light Yellow
7 = White    F = Bright White
*/

set termout on
set timing on