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  1. #1
    Join Date
    Feb 2005
    Posts
    7

    ER diagram help if possible

    Hi there,

    Now im not too good with MS access and even worse with ER diagrams, i was just hoping someone could help me on this project.

    This is what i need to do:

    1) An ER diagram showing all entities, relationships, multiplicity and membership class.

    2) A set of well normalized tables (table types) showing corrent posting of keys to maintain referential integrity and all the data necessary to suport the processing indicated in the scenario in Appendix B

    3) A set of 'assumptions' that you feel are necessary to explain your ER modelling/design decisions.


    Appendix B

    A team of forensic scientists wish to create a 'Crime Scene' database to record details of crime scenes they have worked on. They are concerned that they are failing to take advantage of modern database technology either in recording the findings of their investigations or in searching past cases to seek similarities between cases.

    The following is an extract from an analysis report

    When investigators arrive at a potential crime or investigation scene they firstly establish whether or not the scene has been changed by anyone. If the scene has been changed they record what changes have occurred and details of those that reported the changes to them. They then record the following information about the scene:

    Crime details including:
    Date
    Time (start and end time)
    Location
    Weather
    Name and contact details of the lead Police Officer if involved (if the police are involved)
    Investigators name and contact details of any organisational representitive
    Catergory of crime (commercial (1), fraud (2), violence (3) computer(4))
    For crimes of violence we record additional details about the incident including weapon used severity of injury inflicted, etc.
    We also record a list of items removed for further investigation.
    We also record a list of crime scene observations (short comments) that may be used later to inform our analysis.

    At a later date we also add:
    List of suspects and contact details
    List of witnesses and contact details
    We also need to record the end date of a crime investigation and outcome if known to us.

    End of analysis report


    Ok sorry this is so long, its just i didn't want to miss anything that might be cruicial.

    Thank you in advance if anyone can help.

  2. #2
    Join Date
    Feb 2005
    Posts
    7
    Ive had another look at this and can't figure out where to start, if anyone can help me start it would be much appreciated.

    Thanks.

  3. #3
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    start by identifying the entities

    and don't hold your breath getting a lot of help here, none of us is really all that keen on helping with school assignments when the student shows no effort
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  4. #4
    Join Date
    Feb 2005
    Posts
    7
    No offence but that tone isn't too helpful either, im a university student studying Forensic Science, this is the only IT class we have as everything else is science work. I've looked on websites and have struggled to find the relevant information i need to explain this.

    I can assure you that posting here was a last resort, not for my work to be "done for me", but to ask advice from those who obviously know this alot better than me and maybe get a helping start.

    Sorry if my post caused any inconvenience

  5. #5
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    okay, i can understand your frustration

    start by identifying the entities

    here's a good tutorial --> http://www.utexas.edu/its/windows/da.../datamodeling/
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  6. #6
    Join Date
    Feb 2005
    Posts
    7
    Thank you, im going to have a look through that tutorial and hopefully sort this, thanks again.

  7. #7
    Join Date
    Feb 2005
    Posts
    7
    Hi again,

    Ok im just doing my preliminary tables, im just wondering is there are freeware that i can use for my diagrams?

  8. #8
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002

  9. #9
    Join Date
    Feb 2005
    Posts
    7
    Thank you

    Btw any suggestions from that list for a beginner to ERD's

    ok ive started to sort my entities like you said and these are the ones ive come up with so far, the entities being in bold. I aren't too sure what to do about violence though, as im sure it goes under crime but then that also has information required for it.

    crime details

    ID
    Time
    Location
    Weather
    ContactName
    ContactAddy
    Invesname
    Invesorganisational
    Categoryofcrime


    violence

    ID
    CrimeID
    Weapon
    Injury

    observations

    ID
    CrimeID
    Contactname
    Comments

    items

    CrimeID
    Itemname
    Reason
    Last edited by Rollie; 02-14-05 at 06:46.

  10. #10
    Join Date
    Feb 2005
    Posts
    7
    Ok guys don't laugh but how does this look

    http://www.dbmoulders.co.uk/erd.doc

  11. #11
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    710
    Download and install this for your operating system

    http://www.fabforce.net/downloads.php

    It's free. Post screeshots.


    Your ERD looks okay.

    Now you have to create a logical model.

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