Select list - selecting from a filter

ok. I’m confused…

I have 2 tables:
Category_Table with 2 fields - Category and Sub Category. The data looks like this:
Ford, Escape
Ford, Mustang
Honda, Accord
Honda, Civic

Sales_Table has a bunch of fields but it also has Category and Sub Category. I can do a lookup from list on the Category by saying =Category_Table.Category.Unique() and it works perfectly.

But how do I have a select list that uses the Sales_Table.Category value from Category_Table?

Any help would be appreciated!

@Kurt_Kessler

Is this for the Sub-Category column? Where selectable Sub-Category options are those children sub-categories that belong to the parent category selected in the Category column?

Something like this?

In the invoices table, first the user selects Service (which is similar to your unique Category), then based on that Job type choices are populated, then Job description.

The only special thing with that template is that if Job type options are all empty, that doc simply reuses Service value as a Job type option — but you’ll easily remove that

P.S. Basically, your formula for select list options would be like:
Category_Table.Filter(Category = thisRow.Category).[Sub category]

I want to select the Sub Categories from the Category_Table. So the logic would be something like this:

Select Category_Table.Sub Category for Category_Table.Category = Sales_Table.Category

Make sense?

Perfect!!! Thank you!