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  1. #1
    Join Date
    Feb 2004

    Unanswered: Normalization question


    I have a table to keep record of changes in certain elements (the table is called "Changes"). The stucture is like this:

    changeId: Autonumber
    elementId: Number (linked to the primary key in table "Elements")
    changeTypeId: Number (linked to the primary key in table "ChangeTypes")
    description: Text

    The "Elements" table is like:

    elementId: Autonumber
    elementTypeId: Number linked to the primary key in table "ElementTypes")
    elementName: Text

    I can notice there's some redundancy in the data, since looking at the changes in table "Changes", I can infer the type of the element subject of the change from two columns. For example, a change involving element 342 (which is type A) has a changetype 23 (which only aply to elements of kind A). So looking at either of those fields, I can tell the change refers to a type A element.

    To make things cleares, the ChangeTypes table contains several groups of typechanges, each group being applicable only to one type of element. I'm "enforcing" this using a combo to show only the values valid to the type of element selecte in the above field.

    The thing is I know there's nothing in the structure to prevent the potential risk of getting inconsistent data (element 34, which is type C, suffering a change 39, whic only applies to type B).

    How can I further split my tables to get rid of this problem ?

    Thanks a lot.

  2. #2
    Join Date
    Nov 2002
    I know your platform is Access, but for us to assist, we'd need some DDL..sample data and expected or desired results in the question would also be a big help...

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    The physical order of data in a database has no meaning.

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