How to find what category have been determined to a genre of songs?

[Leo99]

Sorry if I'm posting in the wrong location.
I'm having trouble to find what the exact genre of the songs. I've searched with google, but still not found.
Only found in songfacts.com, but unfortunately this site just listed: the year of released & history of songs.
Also found in pandora.com, but showing features of songs, not specifically genre.

However, there are many sites contain musics with genres, but sometimes for a particular song is not the same genres.
For example a song: Nothing Compares 2 U by Sinead O'Connor.
The various genres are found, somes are writing genres: Pop, Pop Rock, or somes Slow Rock...

So, could anyone help me where to be found or knowing on the right/fix genre for songs?
Thanks in advance.

[Case]

There is a bit of personal opinion when it comes to music genres. There is no standard, and often people will disagree on the most appropriate genre for classification.
Also, (ID3) tagging software with pre-defined lists have lists that differ in description and list length (number of genres to choose from).

When I fill in ID3 tags on MP3 files, I sometimes check the Similar Items listing on cdnow.com (amazon.com) to find a suitable genre for an album.
E.g. for "I Do Not Want What I Haven't Got", it lists at the bottom of the page:

Look for Similar Items by Category
Music > Alternative Rock
Music > Pop > Adult Alternative
Music > Rock
Music > World Music > Europe > British Isles

Look for Similar Items by Subject
Search Music by subject:
Pop
Pop/Rock Music
Rock
Rock/Pop

You could conclude from this that "Rock" , "Pop" and "AlternRock" are all appropriate genres. I'd go with "Pop" for this one, tho'.

Freedb.org lists SOC as "rock", "blues", "newage" and "misc".

Yeah, it's a mess.

[Leo99]

Yes, same problems with me. Sometimes, I'm confused to fill in ID3 tags on my MP3 files.

Ow..but now, I've just found the easiest and most effective way like here:
Please open wikipedia.org, and search by keywords the song's title, then you'll get the song's information completely... a simple, right?
The wiki says that song's genre: Alternative rock, Pop rock.

And if you trouble to fill in ID3 tags cause of no index, please use ID3v2 where you can type whatever you like for example: Alternative Rock or Pop Rock, etc..

OK my problem is solved now. Thanks, mate.