"Oracle Error Collection": Ora-12154:tns: Unable to resolve the specified connection identifier

Believe that this error is not unfamiliar to everyone, only to install the use of Oracle is expected to have encountered this problem, the general is now used in PL/SQL connection to the Oracle database when the time occurs.
The cause of this error and the way of solution are various, I also repeatedly encountered this problem, today, the ORA-12154 to summarize the solution.

1, first look at the server side, the Oracle service and monitoring service is started. Win+r, enter services.msc to view the service. Check whether the two services are executing.

2, through the SQL plus connection to the database to try to exclude server errors. Assuming the SQL plus connection succeeds, it means that the installation process is not error-free and the database is working properly. The error is in some configurations.

3, assume that Sqlplus can successfully log in. Prove that there is no problem with the server. Then start troubleshooting the configuration. Check the Oracle installation folder first: whether the Tnsnames.ora file under D:\app\NiuNiu\product\11.2.0\dbhome_1\NETWORK\ADMIN is configured with the corresponding connection descriptive descriptor. This is to see if a new network service is configured.

Detailed how to configure see blog: http://blog.csdn.net/u010028869/article/details/46652165

Also, be aware of the network service name. There should be no spaces before the DRP, and there can be a blank line between the two services, but there are no whitespace.

You may not recognize a space.

For example, as seen in:

4. View the environment variable-system variable path. Whether there is an Oracle installation folder: D:\app\NiuNiu\product\11.2.0\dbhome_1\bin; This variable is generated by yourself when you install Oracle. It's better to look at the insurance.

5. Assume that the Oracle 10g version number is installed. Open PL/SQL, cancel login, find "Tools->preferences" in Plsql Developer toolbar, find Oracle Home Selection in connection node of Oracle Oraclient10g_ Home1. After saving, close the Plsql Developer, for example, as seen in:

6, assuming that the oracle11g, you need to check whether the Oracle 32-bit client is installed, the corresponding environment variables are configured. Detailed configuration See article: http://blog.csdn.net/u010028869/article/details/46647479

7, assuming that the above methods are not effective after the attempt. Try replacing the Plsql version number, which may be incompatible with downloading the PLSQL and installing the Oracle database version number.

This is the only way to think of the solution in the interim. Hope can help everyone!

"Oracle Error Collection": Ora-12154:tns: Unable to resolve the specified connection identifier