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Re: Data modelling questions.

From: Bill Bunke <bill_bunke_at_pleasantc0.com>
Date: 1997/10/15
Message-ID: <01bcd9b2$a0536fc0$e259a8c0@04687>#1/1

I would suggest that although the original schema did not show a foreign key relationship, it appears that the relationship exists, but the structure
supporting it doesn't. I also think this represents a performance-based design.

If in fact talent_id in the two tables do not represent the same object, it

would appear that there is a need for a naming standard to indicate the difference.

Re: your type-1 and type-2 example, you might be missing a table that indicated the talent (perhaps skill is more precise) and of which type it was
such as skill_list (skill_id , skill_type, skill_name).

This lets you use a table (person_id , skill_id) as you suggest, to accomodate
any number of skills without growing the number of skill columns.

victor tsien <vtsien_at_anl.gov> wrote in article <34451728.38AF_at_anl.gov>...
> Hi, Robert, usually for 1:1 relationship, you will put them into one
> entity. However, with wharehousing and other applications you may need
> to split them if you want to increase the performance. If it were not
> for special purposes, I'd feel it like 5nf. There is no relation
> between talent and talent photo. But each has an id associated with
> it. Another example is a group of people with two type of talents.
> Type 1 - langueages, such as English, Spanish, German, Japanese, etc
> Type 2 - football, tennis, baseball. You can put them into one table
> as:
> (person id, talent type1, talent type 2). But what if some people has
> only talent type 1 or talent type 2. Some people have both. In that
> case you split into two entities: (person id, talent type 1) (person id,
> talent type 2).
>
> The second group:
> Talent (talent_id, talent_name)
> TalentPhoto (talent_photo_id, talent_photo, talent_id)
>
> I'd feel more like a 1:M relationship with 1 talent_id has many
> talent_photo_id senario. Otherwise there is no need to do this way.
>
Received on Wed Oct 15 1997 - 00:00:00 CDT

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