Against what bases are queries against your data evaluated? If you only expose a single “data base” that changes over time, then data citations cannot be a combination of query and basis. When citing a passage in a book, the edition/variation of its publication, i.e. the thing that is assigned an ISBN, is the basis. Optionally, a citation may include a “query” against this basis – a page number, page range, chapter number/title, etc.