I have these 3 scenarios:

Rooms located in a house are assigned a room number within that house - thus, for example, each house has a room number 1. Each room has a phone number etc...

My guess is we do not need to have a separate entity for rooms since each house must have one room then if we delete the room we should delete the house anyway?

A tour guide(identified by tour guide id) may have one or more specialisations but not all tour guides have them.

Specialisations should be a separate class?

If an activity is performed by a Tourism Provider do not record the details of the Tourism Provider who completed the activity.

Should Tourism Provider even be a separate entity because we are not recording the details?

  • 1
    "Rooms located in a house are assigned a room number within that house" seems to me to allow multiple rooms in a house (which seems more reasonable than saying there can only be 1). It also states that the room numbers in each house start at 1 (which affects the logical id of a room). So rooms very definitely need a separate entity. – simon at rcl Apr 7 at 11:52
  • If the scenario specifically says not to record details of the entity should it even be modelled in the diagram? Referring to the updated third scenario. – Sook Lim Apr 7 at 12:11
  • Take that to its logical extreme: you'll have a completely empty diagram with no entities. – simon at rcl Apr 7 at 16:10

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