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Thread: Erd

  1. #1
    Join Date
    Dec 2005
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    Unanswered: Erd

    Attached is my ERD that I'm working on for my Oracle class. It is for an animal shelter. I was wondering whether anyone could give me feedback on the design.

    Thanks.



    Assumption:

    * Animals stay in their shelter until adoption.
    * A person may donate multiple animals and adopt multiple animals.
    * A person may give several donations.
    * A person may receive several thank you cards for his or her adoptions.
    * A person may return an animal that they adopted.
    * A person cannot adopt and return an animal and later adopt the same animal again.
    * An animal must be donated by one and only one person.
    * An animal may change cages temporarily.
    * An animal may receive the same medical procedure multiple times.
    * An animal can receive care from more than one physician.
    * An animal does not have a last name.
    * Each animal shelter has more than one animal.
    * Each piece of medical history of an animal is done by one and only one doctor.
    Attached Thumbnails Attached Thumbnails ERD.JPG  

  2. #2
    Join Date
    Jul 2003
    Posts
    2,296
    I don't like it.
    You use "ID" to descibe all sorts of columns. Be specific. If it is a cage, then
    call it a CAGE_ID. If it is a shelter then call it SHELTER_ID. Descriptive column
    names are important. Especially when you have a high level diagram that non
    IT professionals are reviewing.
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  3. #3
    Join Date
    Jul 2003
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    also, none of your relationships show up in the child tables.
    I need to see PHYSICIAN_ID or OWNER_ID in their respective child tables.
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  4. #4
    Join Date
    Sep 2002
    Location
    UK
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    Provided Answers: 1
    Mr Duck, the poster is correct to use ID the way he/she has. These are not table definitions, but analysis entity definitions, using the "Barker" ERD notation that is the Oracle Designer standard. Foreign key attributes are not shown in this notation, they are inferred from the relationships. Also, it is standard practice to omit the table prefix from attribute names.

    Oracle Designer has a table design generator that takes entity definitions like these, (optionally) prefixes column names with a table prefix, and adds foreign keys columns to support the relationships from the ERD.

  5. #5
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    Provided Answers: 1
    * An animal must be donated by one and only one person.

    Your ERD shows that each Animal may be donated by many Persons via Animal Donation.

    Also, your Cage History entity has no UID.

  6. #6
    Join Date
    Dec 2005
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    5
    Thank you for your help. I appreciate it.

  7. #7
    Join Date
    Jul 2003
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    2,296
    Quote Originally Posted by andrewst
    Mr Duck, the poster is correct to use ID the way he/she has. These are not table definitions, but analysis entity definitions, using the "Barker" ERD notation that is the Oracle Designer standard. Foreign key attributes are not shown in this notation, they are inferred from the relationships. Also, it is standard practice to omit the table prefix from attribute names.

    Oracle Designer has a table design generator that takes entity definitions like these, (optionally) prefixes column names with a table prefix, and adds foreign keys columns to support the relationships from the ERD.
    thanks for the education. Most of my designing has been done in ERwin
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  8. #8
    Join Date
    Sep 2004
    Location
    London, UK
    Posts
    565
    As a diagram layout preference, I like to see parents above children.

    I agree with Tony, the physical design can take care of column naming.

    Good to see soft boxes for entities btw. Hard boxes are for tables. I would remove all underscores as well.
    Last edited by WilliamR; 12-16-05 at 21:02.

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