Self Cross Join?

rubyonrails-talk
1

I have a table with an integer column. I want to retrieve pairs of records where this integer sums to a total. For example:

4|red 6|blue 2|yellow

If I want pairs that add up to 8 I should get [[red,red],[blue,yellow], [yellow,blue]]. Writing the query myself I would just use a join with no ON clause (I think this is a cross join):

SELECT a.color, b.color FROM mytable a INNER JOIN mytable b WHERE a.value + b.value = 8

This works just fine from a sqlite console, but when I try to use find_by_sql I can't get all of the information. It attempts to fit everything into an instance of the model class, which means that I only see b.color.

What is the 'rails' way of doing what I am trying to accomplish? Is there a set of options I can use with find to recreate this query and get both colors out? I'm hoping for an array of 2-element arrays.

2

You'll need to alias one of them (ie b.color as something_else). If what you get back doesn't really correspond to an instance of your class then using connectiion.select_all might be a better fit

Fred.