RESOLUTION 1:
1. Shut down Toad for Oracle.
2. Right click on My Computer and select Properties. Click on the 'Advanced System Settings' link on the right hand side. Click on Environment Variables button.
3. Under System Variables, click the ‘New’ button.
4. For Variable name, enter TNS_ADMIN.
5. For Variable value, enter the directory that contains your TNSNAMES.ORA file.
Click OK until one returns to the Desktop.
*Note if one has other Oracle clients installed on the machine the TNS_ADMIN variable will force the same TNSNAMES.ORA file on all installed clients. If need be, alter the TNS_ADMIN variable to the appropriate directory.
6. Launch Toad. At the connection window, select the TNS tab. The connection window lists the databases from the TNSNAMES.ORA file specified in TNS_ADMIN variable.
7. Select a database; enter the User/Schema name and Password. Click Connect to connect to the database.
RESOLUTION 2 for Oracle 12c:
Follow these instructions which have been known to work with Toad for Oracle:
To download an Instant Client, go to the following link:
Select the “instantclient-basic-nt-12.1.0.2.0.zip” file to download.
NOTE: If you wish for the SQL Plus tool for the Instant client, then you can also download the "instantclient-sqlplus-nt-12.1.0.2.0.zip" file.
A. Extract all Instant Client files to one directory file length path.
Example: C:\Ora12c_32bit
NOTE: If you downloaded the SQL Plus tool, extract all the files to the same location as the Instant client files. i.e. C:\Ora12c_32bit.
B. Place the new Oracle_Home path of Instant Client to the Environment Variable PATH.
1. Right click on My Computer and select Properties.
2. In the Advanced tab select "Environment Variables" button.
3. In the System Variables section, highlight Path and press edit. Edit your path so that your Oracle Instant Client directory path is first.
For example: PATH=C:\Ora12c_32bit;
NOTE: Ensure you have a semicolon at the end, no space.
4. Click OK on all windows.
C. If planning to use TNSnames.ora file to Connect do the following:
1. Right click on the Computer icon on your Desktop and choose Properties option.
2. In the System window click on Advanced system settings link in the left pane.
3. In the System Properties window select Advanced tab and click on Environment Variables button.
4. Under the System variables section of the new window, NEW button.
5. Enter TNS_ADMIN for the variable name and for the variable value type in C:\TNSnames.
6. Manually create a folder called TNSnames in your (C:) drive and paste your TNSnames.ora file there
Confirm that the path to OCI.dll is in system PATH.
The video suggests there is a TNS_ADMIN environment variable setup and that the home is properly listed in PATH.
