ORA-12154, ORA-12560 - Cannot Connect to the Oracle Database

These are some common errors for new installations. The solution pretty simple.
Errors like:
ORA-12154, ora-12560

Listed below are a few of the problems we faced...with a few things to check.

1. SQL+ does not connect to the DB - Check to see that the fire wall on the DB server is not blocking the port (usually 1521) - You can either turn off the firewall or get the system admins to open up the database port.
Also make sure that the listener is up and running.

2. When creating the ODBC connection, we could not test the database connection. - Again make sure the DB listener is turned on and the TNSfiles are copied over from the DB server to the server you are trying to connect from. Copy the files to the location similar to : \Network\Admin\

3. Sometimes you can simply re-install the DB client (Its easier than debugging)

Google is extremely helpful with the ORA-XXXX errors that the DB Connection might throw.

Hope this helps.

Anisha