Help! I can’t connect to my database …

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32 thoughts on “Help! I can’t connect to my database …

  1. Thanks for this basic concept, most new dba, including me when I started, had problem understanding this concept and yes you presisely said it as it shoudl be.

    Again, thank you.


  2. I am getting a ora 12514 i have 3 tnsname servers defined in the tnsnames.ora file and i am unable to connect can you please guide me on how to solve the problem here is the link on oracle forum
    you can reply on your blog or on the forum i will be thankful

    • OK, I’ve started participating in your thread on OTN. Please let me point out that you made two posts here, just one minute apart. While I want to help people, you must understand that a blog is not a chat room. I only check in here once a day, if that. Your question is much better addressed on an OTN forum, where you were already getting what appears to be some very good assistance.

  3. Hi guys
    I have a serious problem im using Oracle9i on Windows xp Sp3 (working on the local computer ) when i try to connect to my local database it shows me ( tnslsnr.exe has encountered a problem and it will close ) no listener any ideas please would be a pleasure

    • I read through it, and don’t really see anything I can add. I do have some concerns about all those ORACLE_HOMEs on a Windows box, especially since on of them is for XE, which pretty much assumes it is the only oracle product installed.

  4. Why this “ORA-12170 TNS Connet time out occured” error raised?
    I am using oracle database 10g on windows xp.

    • I have no way of knowing why any particular ORA-12170 occurred on someone else’s system. Have you tried to google “ORA-12170”? There only about a bazillion hits for that one. Just off the top of my head I’d say you probably have a firewall issue.

  5. Thanks man…. Was stuck on a very tiny issue that had to do with the difference between the service vs SID and your article gave me such an idea to try….. 2 weeks of searching around for answers…. one article and bingo… 🙂 Cheers

  6. Hi

    Just to check in your example above, is “myserver” a typo? Should it be “myhost” instead? Great article by the way.

    • It was a generic example. I could just as easily have written ‘Maybe there was an entry for “fred” in the local hosts ‘, or ‘Maybe there was an entry for “vblnxsrv01” in the local hosts ‘

  7. You need to add another entry where there isn’t a need for tnsname.ora on the client side. There is something called easyconnect!

    • I am aware of easyconnect, but never thought to write about it because it rarely comes up when people are trying to debug connection failures. I’ll see if I can’t put something together on it this weekend. Thanks for the reminder.

  8. Excellent article that explains this process clearly and efficiently! Wish Oracle did it this well. Thank you. I am now a loyal fan of this site.

  9. I just got a 12560 error on a windows vm while trying to connect as sysdba from the windows cmd. The xe had never finished shutting down. The apparent cause was a 50M listener log file. Shutting down that, renaming log file, starting listener, starting db service and protocol errors mysteriously vanished.

  10. Hi Ed,
    You are a great teacher. I’m trying to learn Oracle on my own. I have installed 12c. This article clarifies all the basic things I want to know about Oracle connection. Thanks for the blog.

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