Re: RA with MV attributes
From: Jon Heggland <jon.heggland_at_idi.ntnu.no>
Date: Wed, 17 Jan 2007 08:45:07 +0100
Message-ID: <eokk60$d9$1_at_orkan.itea.ntnu.no>
Date: Wed, 17 Jan 2007 08:45:07 +0100
Message-ID: <eokk60$d9$1_at_orkan.itea.ntnu.no>
David wrote:
> Example
>
> r1(Names,Cars)
> bill, car1,car2,car4
> john,fred car3
>
> r2(Cars,Colours)
> car1,car3,car4 red
> car2 green
>
> r1 |X| r2 (Names,Cars,Colours)
> bill car1,car4 red
> bill car2 green
> john,fred car3 red
> john,fred green
>
> [...]
> For example the
> last tuple of r1 |X| r2 above doesn’t imply that John and Fred
> don’t own any cars.
So what exactly does that last tuple mean?
-- JonReceived on Wed Jan 17 2007 - 08:45:07 CET