How to Correctly Model Captains and Players in an NHL ER Diagram?

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Discussion Overview

The discussion revolves around modeling entities in an Entity-Relationship (ER) diagram for a database representing the National Hockey League (NHL). Participants explore the relationships between teams, players, and captains, as well as the appropriate use of generalization in this context.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant presents a set of requirements for an NHL database and questions whether "ISA" can be used to relate captains and players in the ER diagram.
  • Another participant suggests that a functional dependency diagram is typically used, but acknowledges the context of the question requires an ER diagram.
  • There is a challenge regarding the distinction between "captain" and "player," with one participant asserting that treating them as separate entities may be a mistake.

Areas of Agreement / Disagreement

Participants express differing views on whether "captain" and "player" should be modeled as separate entities, indicating a lack of consensus on this aspect of the ER diagram.

Contextual Notes

Participants have not resolved the implications of using generalization in this context, nor have they clarified the definitions of the entities involved.

shivajikobardan
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Homework Statement
My main confusion is can I use "ISA" in captain and player? Can I use generalization there?
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Suppose you are given the following requirements for a simple database for the National Hockey League (NHL):
1) the NHL has many teams,

2) each team has a name, a city, a coach, a captain, and a set of players.

3) each player belongs to only one team,

4) each player has a name, a position (such as left wing or goalie), a skill level, and a set of injury records,

5) a team captain is also a player,

6) a game is played between two teams (referred to as host_team and guest_team) and has a date (such as May 11th, 1999) and a score (such as 4 to 2).
Here's my solution. Is it correct?
_x1alSrtX1a24LpxNl7LpFD-UbpUUr0TCYqfYOFCNXui8u53vA.png

My main confusion is can I use "ISA" in captain and player? Can I use generalization there?Here's the solution to this problem.
https://www2.cs.sfu.ca/CourseCentral/354/louie/Chap2_practice_key.pdf
 
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Don't you usually do a functional dependency diagram?
 
WWGD said:
Don't you usually do a functional dependency diagram?
Not when the question asks for an entity relationship diagram :-p (see the title)
shivajikobardan said:
Homework Statement:: My main confusion is can I use "ISA" in captain and player? Can I use generalization there?
No, your main confusion is that you have two different entities for "captain" and "player".
 
pbuk said:
No, your main confusion is that you have two different entities for "captain" and "player".
Hmm, so that's a mistake in your opinion?
 

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