The following is the ER model provided with the Beatles sample database and explored in the first lecture videos on ER models. 

Our design has been discussed with the intended client and a fundamental issue uncovered. The proposed database has a songs entity that represents songs as a composition (title, composer) but does not capture the notion of an audio recording of the songs. Also the playlist_tracks relationship is placing the written version of songs on playlists rather than an audio recording of the song. For this problem we want you to redesign the database ER model to incorporate the following requirements.

R3.1) There should be a concept of an audio recording (e.g. mp3, or wav file) of a song.

R3.2) A song composition (i.e. title, composer, etc.) could be recorded multiple times. That is, there could be many recordings of a composed song.

R3.3) The tracks that appear on an album should refer to audio recordings of songs (not written compositions of songs).

R3.4) It should be audio recordings of songs that are placed on playlists (not written compositions of songs).

R3.5) Given an audio recording of a song, it should be possible to determine the composer of the song. That is, to relate an audio recording of a song to the title and composer information about the recorded song.

 

recordings users produc tracks songs playlist tracks playlists