What are the supertype and subtype entities? What is the maximum cardinality of the relationship between EMAIL_MESSAGE and SENDER?

Database Assignment: E-R (IE) Diagram          Name___________________________

For the above diagram

  1. What are the entities?
  2. What are the identifiers?
  3. What are the non-identifying attributes?
  4. What is the maximum cardinality of the relationship?
  5. What is the minimum cardinality of the relationship?
  6. Which entity is strong and which entity is weak?

For the above diagram

  1. What are the supertype and subtype entities?
  2. What is the maximum cardinality of the relationship between EMAIL_MESSAGE and SENDER?
  3. What is the minimum cardinality of the relationship between EMAIL_MESSAGE and SENDER?
  4. Is SUBJECT a weak or strong entity?

 

 

 

For the above diagram:

  1. Give an example of a strong entity.
  2. Give an example of a weak entity.
  3. Give an example of an ID dependent entity.
  4. What is the maximum cardinality of the relationship between COMPANY and STOCK QUOTE?
  5. What is the minimum cardinality of the relationship between COMPANY and STOCK QUOTE?
  6. What is the identifier for the STOCK QUOTE entity?
  7. Create an E-R diagram for a scenario where we need to store the attributes listed below, give the entity a name, include the identifier and attributes, and use crow’s foot notation to show minimum and maximum cardinality. (hints: use only these attributes—don’t make up new attributes for this assignment; this will require two entity classes, i.e. two entity rectangles in your diagram; each PlaylistName must map to at least one song, but songs do not have to be a part of a playlist; a single song can be on multiple playlists and a single playlist can map to multiple songs)

 

PlaylistName

NumberOfSongs

PlaylistLength

SongTitle

SongArtist

SongPlayLength

 

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