SQL & PL/SQL

I am wanting to create a field that checks another field in the same table. If the field checked is a specific value I would like for the "boolean" field to be shown as Y for "yes".

Example:

FIELD 1 | FIELD 2 | FIELD 3
Friend Random Y
Enemy Random N

So the idea is that field three will automatically populate with "Y" when Friend is entered or "N" when enemy is entered. I am attempting to do this in Oracle.

Any help would be appreciated, someone told me to look into ISLEAF, but I am clueless on that. Tried searching didn't find much.

Thanks in Advance!