Is it possible to amend the 'Search SQL' value against an advanced search select when a selection field value changes?

I have a selection with 3 values and a 'Product' search select field.

All I want to do is automatically filter my product search based on the selected value.

To further complicate my selection is going to be set based on a workflow button but I'd like both the selection and product search on the same screen....

Thanks for any suggestions.