RESOLUTION 1:
Configure the path to SQLLDR.EXE.in the Toad options:
1. In Toad, go to View | Toad Options, from the main menu.
2. In the new Window select the Executables item on the left.
3. In the "SQL*Loader" field, click the "Auto find" flashlight button OR checkmark the "Auto detect paths for current Oracle Home" check-box. This will populate the field with the location of the SQL*Loader executable from the Oracle client Toad is connected with.
4. Click "Apply" and "OK" to accept the changes.
5. Restart Toad.
6. Now proceed to launch the SQL*Loader.
RESOLUTION 2:
If SQL*Loader executable cannot be found or does not exist on the systme, then this application needs to be installed in order for it be used in Toad. Please install the full Oracle Client software and then try to configure the executable again in Toad.
When installing the full client, choose 'Administrator' in the Oracle Installation Wizard.
Note: An instant client does not come with the SQL Loader executable by default. You need a full Oracle client installation. The client installation can be downloaded from Oracle's site, or check with your DBA or admin to get the full Oracle client installation.
