Announcements:
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Next monday: Lecture starting 2:30PM (regular class time)

Full review of course material before class



Content to review today:
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Hierarchies 
Weak Entities

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Albums(Id)  key:id

Track as strong entity
Tracks(Id, trackno) key: id



Track as weak entity:
Albums(Id,Title)  key:id
Tracks(AlbumId, TrackNo, notes, duration, songId)  Key: AlbumId, TrackId
Song(Id, Name)  Key: id


Potential weak entities:

-> Episodes  (supporting entity: TVShows), key: SeasonNo, EpisodeNo
-> ProfileListItems (supporting entity: Profile), key: rank
-> Profiles  (supporting entity: Subscribers), key: name

-> Pictures  (supporting entity: Media), key: ????  No natural way to map to weak entities


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Convert the new ER diagram to relational data model
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Media((mediaid), name, releaseyear, desc)

Movies((mediaid))
TVShows((mediaid), channel)

Genre((name))
MediaHasGenre((mediaid, genrename))
Pictures((id), file, mediaid)

Actors((actorid))
StarsIn((actorid, mediaid)

Subscribers((userid))

Profiles((userid, name))

ProfileListItems((userid, name, rank), mediaid)


Episodes((mediaid, seasonno, epno), ...)

WatchEpisodes((userid, name, mediaid, seasonno, epno), date, minutes)

WatchMovies((userid, name, mediaid), date, minutes)