ORA-12154 TNS: could not resolve the identifier

[cristianero_oliveira]

I installed Oracle 10 Express Edition with Delphi 7 in the Windows 7 operating system. Assigns the required grants, create tables by the bank administrator normally. However, when delphi and I try to insert a bench connector by dbexpress, ADO, etc. appears the message
ora 12154-TNS: it was not possible to resolve the connection identifier specified.

[victorhugomuniz]

This is a mistake that often appears in our forum, even if there are many topics about this problem, there seems to be little understanding about error and its solution.
Let's try to set up a tutorial, with the main reasons and the main solutions adopted in this type of problem.

Basically this is a connection problem between the client and the database.
So let's put in priority the actions, even if basic and even ridiculous, but it has to be looked at and discarded before looking for more complex solutions.

On the server:
1. Verify that the server is on the network, using the ping command both the client for the server and the server to the client, it is necessary to verify that the traffic is available in both hands.
2. Check that the bank is in the air, that is, if the boot process occurred without fail.
2.1. See the Alert that is in the BDump directory configured during the creation of your bank if the bank has been successfully initiated.
2.1.1. Sometimes the process is apparently in the air, but for lack of memory or by a boot failure the bank stayed in stand by.
3. Verify that the listener is working properly.
3.1. Check in the $ Oracle_Home / Network / Log directory. Listener.log
4. Verify that the Listener configuration.ora, sqlnet.ora and tnsnames.ora, which are in the $ Oracle_Home / Network / Admin directory, are correct.
4.1. In the tnsnames.ora file you have to exist and to be in the listed directory, you must also contain the names.directory_path values ??of the sqlnet.ora
5. Check the number of concurrent connections in the Bank Boot file.
6. The directories where both binary (programs) files and datafiles (database) should be owned by the user who will start the bank, this user should never be root or administrator.
7. Try to connect to the bank using SQLPlus, if it fails and no use trying to go to the client, check the error, and if everything is OK, contact the forum personnel, identifying the error and what has already been verified.

In the client:
1. Check the TNSNAMES and SQLNET configuration, which are in the $ Oracle_Home / Network / Admin directory, check out the data to see if all are correct, mainly host name, port, and bank name (SID)
. Run tnSping with the name of the alias that is in TNSNAMES, the same must successfully return the test.
3. Try the connection using SQLPlus, if this fails to check the possible causes of the error.
4. Test the connection using the application.

Any error not covered in this article should be notified to the group so that we can jointly assist in solving its problem in addition to improving this tutorial.

Note: On the site http://www.ora-code.com you will certainly find some more tips, not only for this error as for many others, only in English

ORA-12154:
TNS: Could Not Solve The Connect Identifier Specified
Cause: Connection To database or other service was required using Connect Identifier, and The Connect Identifier Specified Could Not Be Resolved Into Connect Descriptor Using One of the Naming Methods Configured. For example, IF The Type of Connect Identifier Used Was The Net Service Name Then The Net Service Name Could Not Be Found In The Naming Method Repository, or The Repository Could Not Be Located Or Reached.
Action:


- If you are USING LOCAL NAMING (TNSNAMES.ORA FILE):

- Make Sure That "TNSNAMES" is listed as one of the values ??of the names.directory_path parameter in the oracle net profile (sqlnet.ora)

- Verify That to TNSNAMES.ORA FILE Exists and IS IN THE PROPER Directory and is accessible.

- Check that The Net Service Name Used The Connect Identifier Exists in the tnsnames.ora file.

- Make Sure There Are No Syntax Errors Anywhere in The Tnnames.ora File. Look for UNMATCHED parenthes or stray characters. ERRORS IN A TNSNAMES.ORA FILE MAY MAKE IT UNUSABLE.

- If you are using Directory Naming:


- Verify That "ldap" is listed as one of the values ??of the names.diretory_path Parameter in the Oracle Net profile (sqlnet.ora).

- Verify That The LDAP Directory Server Is Up and That Is Accessible.

- Verify That The Net Service Name or Database Name Used The Connect Identifier is Configured in the Directory.

- Verify That The Default Context Being Used Is Correct By Specifying A Fully Qualified Net Service Name or A Full LDAP DN AS THE CONNECT Identifier

- If you ARE USING EASY CONNECT NAMING:

- Verify That "ezconnect" is listed as one of the values ??of the names.diretory_path parameter in the oracle net profile (sqlnet.ora).

- Make Sure The Host, Port and Service Name Specified Are Correct.

- Try Enclining The Connect Identifier in Quote Marks. See The Oracle Net Services Administrators Guide or The Oracle Operating System Specific Guide for More Information on Naming.
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