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Assistance defining cardinality in an Entity Relationship Diagram required

Posted on 2009-02-22
Medium Priority
Last Modified: 2012-05-06
I'm creating a ERD for a hotel with leisure facilities who are moving from a manual system of reservations and would appreciate some assistance in defining the cardinality of the Entities in said ERD.  Here's an outline of the Entities (in caps) and their relationship with one another -


GUEST books and participates in ACTIVITIES


I've already created the ERD but am having trouble defining cardinality, any suggestions with detail would be much appreciated...  SP
Question by:spower22
LVL 36

Accepted Solution

Gary Patterson earned 1200 total points
ID: 23705978
There is an awful lot of decent hotel software out there already built, tested, debugged, and working.  Do you really want to build something that you can buy for $200:

http://www.imagichotelreservation.com/ (just and example - I haven't used it - but it looks like there is a free trial available.)

Also, if you haven't already, take a look at aoy of these open source hotel projects.  Even if you don't adopt one as your starting point (and why wouldn't you?), you'll certainly get ideas for features and structure:


Anyway, here's a shot at your relationships.

RESERVATION : ROOM - Association
GUEST : ACTIVITY: Association


In a real life the relationships may be a bit more complex, since there may also be entities such as is also the relationship to ROOMTYPES (reservations are typically made for a given room type, rather than a specific room) and perhaps ACCOUNT - a method of aggregating charges for a group of rooms, or for billing non-guests for banquet or activities.

Hope this helps.

- Gary Patterson

LVL 35

Assisted Solution

by:David Todd
David Todd earned 800 total points
ID: 23707876

To echo and enlarge on Gary's thoughts above, there is a lot of software out there.

A guest's stay is a process
make a booking
confirm a booking
change the booking
check-in and room assignment!
hotel's nightly process charges for room
pay bill

Rather than start by modelling the static data, I would model the process. The process will require different states to be saved at different times.

If you end up building something, make very sure that even if it does't have that many features, that each feature is very resiliant. Hotels tend to be busy places, with some of the less IT Savy folk, and often at night staffed by folk on minimum wage. It seems that people skills and IT skills are on opposite ends of a personality continuim. That is, it has to be EASY to use and DIFFICULT to crash.

I've done my time supporting a product called Hotelier Plus, so I've a little experience in where you are going ...


Author Comment

ID: 23709672
Thanks for the information, that helps a lot.  Having look at the existing options I reckon I'll go with one of those and customise it to our requirements.  SP

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