Why do i see the 'ora-12154: tns:could not resolve the connect identifier specified'?

This error usually arises when trying to connect to an Oracle database and there's an issue with locating the service.

Example:

ORA-12154: TNS:could not resolve the connect identifier specified

Solution:

1. Ensure your 'tnsnames.ora' file exists and is properly configured.
2. Verify your 'TNS_ADMIN' environment variable points to the correct directory.
3. Test with 'tnsping'.