As a developer you have to deal with several different databases. It's not easy to keep all of your environments in mind. Let's use Org-mode to help yourself.
Keep an environment's description in "org-mode" table:
Place the point to a connection line, call sqlplus-x-connect and you will get connected sqlplus-mode buffer. If different users have the same password you can write them in one cell.Here is the sqlplus-x-connect
Advice. Use EasyPG package to keep your connections table in secret.