My public library had a few (three?) Books with indexes of melodies for identification. One was filled with national anthems, one with classical themes IIRC. So the idea is you whistle a tune, write an asterix for the first note and the u, d or r for each consecutive note depending on weather it the melody moves up, down or repeats tje previous note. Any melodi can be identified with this method, if you take a long enough string into consideration.
This was in the age of dead trees, a digital, online index would be much easier to maintain and search.