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Starting the ER Diagram Assignment

The following is an activity that I would like the teams for the ER assignment to do together in class on Wednesday.

Context:

  • I have assigned partners based on your stated availability. I've done my best, but it will probably still be difficult to find times to meet.
  • I'll give each team a printout of the overlap in their free time. I expect you to do your best to work as a pair.

Your goals for today:

  • Get to know each other a bit
  • Discuss when and where you will meet to continue working on the assignment
  • Begin working on the assignment

Norms for Pair Work

I expect that each person will agree with the following norm for pair work:

  1. Be present for each meeting, arriving on time (barring emergencies) and being fully engaged during the meeting.
  2. Respect one another.
    • Everyone has something to contribute
    • Everyone deserves to be heard
    • Everyone has an obligation to listen and to speak
  3. The work should be joint work.
    • Don't work on your own; let your partner contribute
    • Don't expect your partner to do the work

what's missing?

  • What norms are missing?
  • How else can we show respect?

Why does this matter?

Getting to Know Each Other

As before in this class, introduce yourself and try to find a few non-trivial things that you have in common, such as a favorite food, song, movie, book, hobby, or lots of other possible things. Plan to chat for 5-10 minutes.

Find another pair and introduce your partner to that pair.

Scheduling

Talk about when and where you will meet to continue the work on the assignment. I will hand out info to make it easier.

Assignment Work

Each of the problems requires the following:

  • Entities: what kinds of things need to be represented in the database?
  • Attributes: what attributes (properties) do those entities have? Come up with a few important ones, not a million. If the entity is car, attributes might be make, model, year, color, but then that's probably enough.
  • Keys: what is the unique identifier for each entity? For example, cars have a VIN.
  • Relationships: how are the entities related? Are those relationships one-to-one? one-to-many? many-to-many? Given one entity, how do you find the related entities (the foreign keys).
  • A diagram illustrating the above

The entities, attributes and relationships will not always be obvious. So, here's what to do:

  1. Each partner thinks about these things on their own for 5 minutes, coming up with some ideas
  2. Then, you discuss together.
    • If you agree; great. You can proceed
    • If you disagree, that's good too! You can use the discussion to better understand your partner's view of the problem.
    • Feel free to discuss issues with me
  3. Sketch, on paper, some ideas for the diagram

I suggest you do not start working with dbdiagram.io until you and your partner have come to some agreement on the enties, attributes and relationships for a problem and have a sketch of your own.

Conclusion

These discussions will probably take up the balance of our Wednesday class. Continue working on the assignment outside class.

Good luck!