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About database design

Started by"Tony Johansson" <johansson.andersson@telia.com>
First post2015-01-25 15:30 +0100
Last post2015-01-26 08:33 -0800
Articles 4 — 4 participants

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  About database design "Tony Johansson" <johansson.andersson@telia.com> - 2015-01-25 15:30 +0100
    Re: About database design Erland Sommarskog <esquel@sommarskog.se> - 2015-01-25 18:18 +0100
    Re: About database design --CELKO-- <jcelko212@earthlink.net> - 2015-01-26 07:34 -0800
      Re: About database design rja.carnegie@gmail.com - 2015-01-26 08:33 -0800

#1860 — About database design

From"Tony Johansson" <johansson.andersson@telia.com>
Date2015-01-25 15:30 +0100
SubjectAbout database design
Message-ID<ma2uli$jr1$1@dont-email.me>
I just wonder what relation do we have between Competition and a Rider.
We know that a competítion have many riders in horse jumping..

But can a rider paricipate in many horse jumping competition but not at the 
same time.
So do we have a many to many or one to many in the connection between 
Competition and Rider in horse jumping?

//Tony 

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#1861

FromErland Sommarskog <esquel@sommarskog.se>
Date2015-01-25 18:18 +0100
Message-ID<XnsA42DBA47632Yazorman@127.0.0.1>
In reply to#1860
Tony Johansson (johansson.andersson@telia.com) writes:
> I just wonder what relation do we have between Competition and a Rider.
> We know that a competítion have many riders in horse jumping..
> 
> But can a rider paricipate in many horse jumping competition but not at
> the same time. 
> So do we have a many to many or one to many in the connection between 
> Competition and Rider in horse jumping?
> 

Yes, sounds like a CompetitionMembers table with CompetitionID and RiderID 
as the primary key.


-- 
Erland Sommarskog, Stockholm, esquel@sommarskog.se

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#1862

From--CELKO-- <jcelko212@earthlink.net>
Date2015-01-26 07:34 -0800
Message-ID<ea1f56c5-d603-4d4d-b2ff-73b94413ab98@googlegroups.com>
In reply to#1860
>> So do we have a many to many or one to many in the connection between  Competition and Rider in horse jumping? <<

Where is the horse in this model? A rider cannot be in two places at once, but neither can a horse.  

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#1863

Fromrja.carnegie@gmail.com
Date2015-01-26 08:33 -0800
Message-ID<1a03d515-3f4a-4d74-96a5-6187ed41e180@googlegroups.com>
In reply to#1862
On Monday, 26 January 2015 15:34:39 UTC, --CELKO--  wrote:
> >> So do we have a many to many or one to many in the connection between  Competition and Rider in horse jumping? <<
> 
> Where is the horse in this model? A rider cannot be
> in two places at once, but neither can a horse.

I am not sure whether the rider or the horse
is considered to be the competitor.  But I think
they go together; if one of them breaks a leg and 
must be shot, the other retires from the contest.

I suppose that a "competition" of this sort may
include several scores; time taken, number of 
fences jumped, grooming, not leaving an additional
hazard on the course for the next competitor...

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