In my form, the user enters the product number and store number. I only want to collect unique pairs. Product number 123 from store 1 can be submitted only once. The store number repeats so I cannot mark the field as NO DUPLICATE. However, I cannot mark the product number as NO DUPLICATE because this number may repeat itself in another store.
Is there any way to solve this problem so that if such pairs are found in an already existing entry, validation error is displayed?