The error ORA-12154: TNS:could not resolve the connect identifier specified occurs when the listener could not resolve SERVICE_NAME specified in the connect descriptor.The common causes of this error explained below.
For example
C:\>sqlplus test/test@bsbs SQL*Plus: Release 10.2.0.1.0 - Production on Mon Nov 24 13:51:10 2008 Copyright (c) 1982, 2005, Oracle. All rights reserved. ERROR:ORA-12154: TNS:could not resolve the connect identifier specified
Solutions:
1. Check that the SERVICE_NAME parameter in the connect descriptor of the net service name.In the above example it is ‘bsbs’.
2. Check the entry specified in tnsnames.ora Network Configuration File.
This can be found at your oracle intallation directory.
Ex: C:\oracle\product\10.2.0\db_1\network\admin\tnsnames.ora.
Check the service name specified in the file.Correct it and try connecting again.