It is possible for a attribute to be multivalued in a ___________________ but no

Question

It is possible for a attribute to be multivalued in a ___________________ but not a _________________. (Fill in the blanks to get the best possible answer that can be formed using the terms ‘ER model’, ‘relational schema’, and ‘recursive relationship’.)

In the music library example, a possible entity set is ‘playlist’. If the playlist gives the IDs of tracks, and each track has a ‘length’ attribute (giving how long the track is in seconds), then the length of the playlist could be calculated from the track lengths. So should playlist have an attribute ‘length’ in an ER model? a) yes, b) no, or c) the choice would be a modeling decision. _______

Why might you want to model ‘address’ as a composite attribute (built from attributes ‘street’, ‘city’, ‘state’, and ‘zip’, perhaps) rather than just using all of the individual attributes? Would it be a) because in the model we might want to sometimes refer to the address as a whole and sometimes to parts of the address, b) to save space, or c) to avoid possible null values ______

Suppose a music library model includes entity sets ‘album’ and ‘artist’, and relationship set ‘album-artist’. In this model, would you expect the participation of album in album-artist to be ‘total’? yes/no ___________ Explain your answer: ___________________________ _______________________________________________________________________

Why might it be a bad idea to model the name of an instructor’s department as an attribute of the instructor? Would it be because: a) we might in the future want to allow instructors to belong to multiple departments, b) it is important to model the smallest possible number of attributes, or c) department names can change? (select all that apply) _________

Explanation / Answer

Multiple Questions answering few.

1. a) ER model but not in recursive relationship
2. b) no
3. a) because in the model we might want to sometimes refer to the address as a whole and sometimes to parts of the address,

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.