Re: Selecting pairs of numbers

When in doubt, cheat! Why not something like:

SELECT x, y FROM organ_pipes WHERE point(x,y) <@
box(point(?x1,?y1),point(?x2,?y2)) ;

This is definitely a different approach from the others that I've seen.

Basically, think of your channel / piston as a point in a Cartesian plane.
And your boundaries as a box in that graph. So you see if the "point" is
inside the "box"

On Mon, Oct 5, 2015 at 1:39 PM, Raymond O'Donnell <rod(at)iol(dot)ie> wrote:

> Hello all,
>
> I have an SQL problem which ought to be simple, but I can't get my head
> around it.
>
> I have pairs of integers - let's call them (x, y). In effect, x is a
> category, while y is an item within that category. For every x, there is
> always the same number of integers y; and both x and y are always
> numbered sequentially starting from 1.
>
> My problem is that I need to select a list of these pairs, ordered first
> on x and then on y, from a given starting point to a given finishing
> point and including all pairs in between.
>
> For example, I might have:
>
> x | y
> -----
> 1 | 1
> 1 | 2
> 1 | 3
> 1 | 4
> 2 | 1
> 2 | 2
> 2 | 3
> 2 | 4
> (etc)
>
> I then might want to extract a list from, say, (1, 3) to (3, 2), giving:
>
> x | y
> -----
> 1 | 3
> 1 | 4
> 2 | 1
> 2 | 2
> 2 | 3
> 2 | 4
> 3 | 1
> 3 | 2
>
> For the life of me, I can't figure out how to do this. Any help will be
> appreciated, or even just a pointer in the right direction. There's
> probably something simple that I'm just not seeing....
>
> If anyone's interested, these numbers represent channels and pistons on
> the combination system of a largish pipe organ... it's for a hobby project.
>
> Many thanks in advance!
>
> Ray.
>
>
> --
> Raymond O'Donnell :: Galway :: Ireland
> rod(at)iol(dot)ie
>
>
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