This can be done manually or in a script.
- Enter find mode
- Specify the criteria in your Qty field.
- Select New Request from the Requests menu
- Enter Toyota in the Mfr field.
- Click the Omit button in the status area.
- Perform your find.
Enter Find mode
Set Field [Yourtable::Qty ; ">0"]
Set Field [Yourtable::Qty ; "Toyota"]
Omit Record //in find mode this does the same thing as clicking that omit button
Set Error capture [on]
Perform Find 
While I've used literal string constants with these set field steps, they can also refer to either a variable or a field with global storage specified in order to create a script that uses criteria entered by the user to perform the find.
Excellent. Thanks a lot. I looked all over for an answer and the "omit" was staring right at me the whole time. Never even noticed it.