I have an Oracle tnsnames.ora file from my previous workplace. I want to pick it up with my newly installed PL SQL Developer on another computer. I have copied the file into ..O
If you are certain your tnsnames.ora file is correct (eg by testing the connection with the Oracle Net Config Assistant, or logging in successfully with SQLplus), and you are able to open the PLSQL Developer application, but you still can't connect to the database in PLSQL Developer, then follow these steps:
In PLSQL Developer (version 11.0) go to Help/Support Info
Click the TNS Names tab. If the path in PLSQL Developer is wrong it will be blank (no tns file found) or incorrect (wrong tns file in use)
On the Info tab scroll down to the TNS File entry and to see the path for the tns file PLSQL Developer is using. Very likely this is wrong.
To correct the path:
plsqldev.exe TNS_ADMIN=c:\your\tns\directory\path\here
*path is to the directory containing your tnsnames.ora file - for me this is: c:\Oracle\product\11.2.0\client_1\network\admin
A new PLSQL Developer UI will open and you should be able to connect.
Make sure you have a Windows environment variable TNS_ADMIN set to the same path