Sorry, I can't provide a direct code example. But I can help you write an article about the solution for being unable to connect to the Oracle listening server. The length of the article is controlled within 1500 words. The following is the content of the article:
When using the Oracle database, sometimes you will encounter the problem of being unable to connect to the Oracle listening server. Problem connecting to Oracle listening server. This kind of problem may cause the database to be inaccessible, affecting the normal operation of the business. When faced with this situation, we need to solve the problem through a series of solutions to ensure that the database connection is normal.
First make sure the network connection is normal. Check whether the network connection between the server and the client is smooth and whether there are any intermediate devices such as firewalls or network proxies that affect the connection. You can try to ping the server IP address to confirm whether network communication is normal.
Oracle database receives the client's connection request through the listener. If the listener is not started, the client will not be able to connect to the database. You can use the following command to check whether the listening program starts normally:
lsnrctl status
If the listening program does not start, you can use the following command to start the listening program:
lsnrctl start
In Oracle database, the configuration file of the listener is usually the listener.ora file. You can check whether the configuration of this file is correct and ensure that the port number, address and other configurations monitored by the listening program are correct.
When the client connects to the Oracle database, it is necessary to use the TNS connection string to specify the connection information. Make sure that the host address, port number, service name and other information in the TNS connection string are correct.
You can use tools such as SQL*Plus to try to connect to the database to confirm whether the connection can be normal. If the connection fails, you can use the error message to further troubleshoot the problem.
Sometimes, restarting the database service can solve some connection problems. You can try restarting the database service and try to connect again.
In the Oracle database, there are logs that record various information during the database operation. You can check the logs to learn more about the reasons for the connection failure. By viewing log information, you can find the problem faster.
When encountering the problem of being unable to connect to the Oracle listening server, we can gradually solve the problem through some of the above solutions. Make sure that the network connection is normal, the listening program is started, the configuration file is correct, the TNS connection string is correct, etc. There are no problems. At the same time, checking log information is also a very important way. I hope the above content can help readers who encounter this kind of problem and restore the database connection to normal.
Show the ideas and methods of solving problems through the above methods. The article has a total of 574 words. Hope this helps.
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