Assistance defining cardinality in an Entity Relationship Diagram required

Posted on 2009-02-22
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 34

    Accepted Solution

    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: (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.

    GUEST : RESERVATION - Possession
    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

    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

    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

    Featured Post

    Free Trending Threat Insights Every Day

    Enhance your security with threat intelligence from the web. Get trending threat insights on hackers, exploits, and suspicious IP addresses delivered to your inbox with our free Cyber Daily.

    Join & Write a Comment

    Live is the evolution of Q&A. Get your technology problems solved instantly by connecting with technology experts instantly. Pair programming has never been easier.
    If you want to move up through the ranks in your technology career, talent and hard work are the bare necessities. But they aren’t enough to make you stand out. Expanding your skills, actively promoting your accomplishments and using promotion st…
    Video by: Steve
    Using examples as well as descriptions, step through each of the common simple join types, explaining differences in syntax, differences in expected outputs and showing how the queries run along with the actual outputs based upon a simple set of dem…
    Polish reports in Access so they look terrific. Take yourself to another level. Equations, Back Color, Alternate Back Color. Write easy VBA Code. Tighten space to use less pages. Launch report from a menu, considering criteria only when it is filled…

    729 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    16 Experts available now in Live!

    Get 1:1 Help Now