GoScrobble/docs/removing_bad_data.md

## Removing bad data

This is by no means recommended.. But during testing I somehow scrobbled movies.

    SET FOREIGN_KEY_CHECKS=0;
    DELETE FROM artists WHERE `name` = "%!s(<nil>)";
    DELETE FROM albums WHERE `name` = "%!s(<nil>)";
    DELETE album_artist FROM album_artist LEFT JOIN artists ON artists.uuid = album_artist.artist WHERE artists.uuid is null;
    DELETE album_artist FROM album_artist LEFT JOIN albums ON albums.uuid = album_artist.album WHERE albums.uuid is null;
    DELETE track_artist FROM track_artist LEFT JOIN artists ON artists.uuid = track_artist.artist WHERE artists.uuid is null;
    DELETE tracks FROM tracks LEFT JOIN track_artist ON track_artist.track = tracks.uuid WHERE track_artist.track IS NULL;
    DELETE scrobbles FROM scrobbles LEFT JOIN tracks ON tracks.uuid = scrobbles.track WHERE tracks.uuid is null;
    SET FOREIGN_KEY_CHECKS=1;


Removing duplicates (based on same song played in same hour)

    -- backup stuff first
    DROP TABLE BACKUP_scrobbles;
    CREATE TABLE BACKUP_scrobbles (primary key (uuid)) as select * from scrobbles;

    SELECT BIN_TO_UUID(`user`, true), scrobbles.*, count(*) FROM scrobbles
    -- WHERE `user`= UUID_TO_BIN('<userUUID>', true)
    GROUP BY track, HOUR(created_at)
    HAVING count(*) > 1
    ORDER BY COUNT(*) DESC;

    -- will only delete one set of dupes at a time, run until 0 updated rows
    DELETE scrobbles
    FROM scrobbles
    WHERE uuid IN ( 
        SELECT uuid FROM (
            SELECT `uuid` FROM scrobbles
            WHERE `user`= UUID_TO_BIN('<userUUID>', true)
            GROUP BY track, HOUR(created_at)
            HAVING count(*) > 1
        ) x
    );