Checking if a list is consuming lookup value column or not

Question

I have two lists,

List A [Document Number, Name, Title,...] (document library)
List B [Information Number, Name, Title, Document Number] (simple list)

Now List B is getting all documents from List A as lookup column and letting user add documents name to List B specific Information Number, which can have 0, 1 or many documents.

Now I want to find out if List B has any document assosciated with it or not, but I can't think of any short way of doing it, Can someone recommend me the best way of doing it please.

Answer 1

How about looping through the items in List B and checking if the lookup field value of the item is not null or empty and immediately breaking from the loop.