text: -- insert a new song
  -- can only be used with insert album. cannot use alone.
  -- params: id / name / duration / albumId / mp3url / artists[]
  
  insert into `song` (
  	`id`, `name`, `duration`,	`albumId`, `mp3url`
  ) values (	
  	[], [], [], [], []
  )
  	
  	-- loops
  insert into `song_artists` (
  	`songId`, `artistId`
  ) values (
  	[], []
  )
  
  -- insert a album
  -- required artist exists. 
  -- after this, insert its songs. 
  -- params: id / name / coverUrl / type / subtype / description / publishTIme
  
  insert into `album` (
  	`id`, `name`, `coverUrl`, `type`, `subtype`, `description`, `publishTime`
  ) values (
  	[], [], [], [], [], [], []
  )
  
  	-- loops
  insert into `album_songs` (
  	`albumId`, `songId`
  ) values (
  	[], []
  )
  
  	-- loops
  insert into `artist_albums` (
  	`artistId`, `albumId`
  ) values (
  	[], []
  )
  
  -- insert a artist
  -- params: id / name / briefDesc / avatarUrl / trans
  insert into `artist` (
  	`id`, `name`, `briefDesc`, `avatarUrl`, `trans`
  ) values (
  	[], [], [], [], []
  )
  
  -- insert a playlist
  -- params: id / name / coverUrl / description
  insert into `playlist` (
  	`id`, `name`, `coverUrl`, `description`
  ) values (
  	[], [], [], []
  )
  
  	-- loops
  insert into `playlist_songs` (
  	`playlistId`, `songId`
  ) values (
  	[], []
  )