the Unix box have a 8.1.5 oracle server, and I just installed oracle 8.1.6 in the same machine using a different ORACLE_HOME directory.
I put different oracle_home directories according to the SID_NAME in the oratab file.

For example
HOST:/export/oracle/app/product/8.1.5:N
CODE:/export/oracle/app/product/8.1.6:N

If I ran profile file whenever I change the ORACLE_SID, Oracle read a right ORACLE_HOME directory, but if I change ORACLE_SID in the shell prompt.

export ORACLE_SID=HOST
echo $ORACLE_SID
>HOST
echo $ORACLE_HOME
>/export/oracle/app/product/8.1.6
then shows me a wrong ORACLE_HOME path.

What do I need to put to the profile file for the user oracle to manage both ORACLE_SID and ORACLE_HOME separately?
Thanks.