Lidarr/src/NzbDrone.Core/Housekeeping/Housekeepers/CleanupOrphanedArtistMetadata.cs

using Dapper;
using NzbDrone.Core.Datastore;

namespace NzbDrone.Core.Housekeeping.Housekeepers
{
    public class CleanupOrphanedArtistMetadata : IHousekeepingTask
    {
        private readonly IMainDatabase _database;

        public CleanupOrphanedArtistMetadata(IMainDatabase database)
        {
            _database = database;
        }

        public void Clean()
        {
            using (var mapper = _database.OpenConnection())
            {
                mapper.Execute(@"DELETE FROM ""ArtistMetadata""
                                     WHERE ""Id"" IN (
                                     SELECT ""ArtistMetadata"".""Id"" FROM ""ArtistMetadata""
                                     LEFT OUTER JOIN ""Albums"" ON ""Albums"".""ArtistMetadataId"" = ""ArtistMetadata"".""Id""
                                     LEFT OUTER JOIN ""Tracks"" ON ""Tracks"".""ArtistMetadataId"" = ""ArtistMetadata"".""Id""
                                     LEFT OUTER JOIN ""Artists"" ON ""Artists"".""ArtistMetadataId"" = ""ArtistMetadata"".""Id""
                                     WHERE ""Albums"".""Id"" IS NULL AND ""Tracks"".""Id"" IS NULL AND ""Artists"".""Id"" IS NULL)");
            }
        }
    }
}