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  1. #1
    Join Date
    Nov 2006

    Question Correct ER Notation - "is a type of which appears in another entity"

    Right, I have this structure (example only).

    UserType2 (uID, areaID, lname, fname)
    CompletedReport (completedID, uID, reportID, dateDone)
    ReportCheck (completedID, reportChecker)

    Where uID's are related and the reportChecker:
    • is a TYPE of User.
    • MUST appear in the CompletedReport table.
    • is such that a reportChecker must have completed a report with the same reportID.

    For example, Bob and Joe completed report R1 with Sam doing R2 (so they are in the Completed Report Table).

    Bob can then check (be the reportChecker) of Joe's report but not Sam's as Sam's is a different reportID.

    If you have understood that so far - how do you illustrate this in an entity relationship diagram? Is this normalised enough?

    Hopefully someone can help.

  2. #2
    Join Date
    Jan 2007
    REAL world examples are far easier to understand, plus you can bet some of your detail is lost in traslation
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