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Thread: DB schema help

  1. #1
    Join Date
    Jul 2011
    Posts
    2

    Unanswered: DB schema help

    Hi guys,

    I am trying to do a database ER for the following scenario but I cannot figure it out how to do it specially the coordinates bit. Has anyone got a clue?

    tks

    PhotoBook is a site for sharing information about places, photographs and arranging meetings.

    Design a database that will enable PhotoBook members to add photos, places and visits.

    Members should also be able to allocate other members as friends who are able to browse all of the information they add.

    Places are identified and named by members. Their locations are described either by a point or an enclosing rectangle. Points consist of a pair of x,y coordinates. Rectangles consist of two pairs of x,y coordinates identifying the north‐west and south‐east corners.

    Members can add unstructured text and any number of optional tags to describe a place. Note that each member may add, describe and locate the same ‘place’ (e.g. Northampton Square) differently, but a member must give each of the Places they add a unique name.

    All photos are associated with a place Photos may also be optionally associated with a visit.

    The date and time at which each photo is taken is recorded in PhotoBook along with file name and a photo number that uniquely identifies each photo added by any individual member.

    Unstructured text and tags can be added by the photo’s owner to describe each photo. Any member who views a photo owned by one of their friends can rank it from 0‐5.

    Visits are periods of time when members are at particular places.
    Members sign up with a unique name. Their full names, dates of birth and time and date of most recent activity must be recorded in PhotoBook.

    For the purpose of this scenario assume that all Places are in Russia. Use the coordinates which should be within the following bounding box:

    North 200,000
    South 150,000

    East 560,000
    West 500,000

  2. #2
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    Quote Originally Posted by italo59 View Post
    Has anyone got a clue?
    sure we do

    but it's ~your~ homework assignment, so we are more interested in helping you work through it

    give it your best shot, post your best effort, and ask specific questions if you're not sure of something

    but don't just dump your assignment on us and ask us to do it for you, 'cause that ain't gonna happen

    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  3. #3
    Join Date
    Jul 2011
    Posts
    2

    Clarification

    The part that I really need help is the rectangle coordinates......

  4. #4
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    seems to me that each place will have 4 attributes, two of which are optional (nullable)

    since you're building an ER diagram, though, the attributes don't come into play yet, since ER diagrams involve only the entities and their relationships

    relationships are built using PKs and FKs and so these attributes are often shown in the ER diagram, but non-key attributes generally are not

    have you got a diagram yet?
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

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