SELECT count(*) FROM Documents WHERE document_id NOT IN ( SELECT document_id FROM Documents_with_expenses )
Count the number of documents that do not have expenses.
SELECT count ( * ) FROM Documents WHERE document_id NOT IN ( SELECT document_id FROM Documents_with_expenses )
select count ( * ) from documents where document_id not in ( select document_id from documents_with_expenses )
Count the number of documents that do not have expenses .