Validate Form Entry Against Table Column

[Haypipi]

I'm trying to create a form for an inventory return, with inputs for staff_id, shop_id, and item_id.

I tried the formula IN("staff_id",staff[staff_id]), but the parameters disappear after.

How can I check these values entered by staff against their respective tables to ensure they are valid entries? I would like to prevent submission if there are errors.