Re: Selecting pairs of numbers - Mailing list pgsql-general

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@iol.ie


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