Rails: selecting columns from multiple tables

ruby-on-rails, sql

Solution

If you modify your `:select` clause to read:

foo = a.find(:all, 
       :joins => [:b, :c], 
       :select => "distinct b.b2 as b2_value, c.c2 as c2_value", 
       :conditions => {:a => {:a1 => Time.now.midnight. ... Time.now}}, 
       :group => "b.b2, c.c2")

I believe you will retrieve an array of records. Then try the following:

b2_value = foo.first["b2_value"]

That should retrieve the value you are looking for.

Also, note that in the query I specified the table name with the columns wherever I used them -- I think it's better practice and will also avoid bad queries when you have duplicate column names (for example, `created_at` or `id`).

Problem

I am new to Rails. I have three tables `a`, `b`, `c` `b` has 2 columns: `b1` and `b2` `c` has 2 columns: `c1` and `c2` `a` has 3 columns: `a1`, `b1` (foreign key) and `c1` (foreign key) I want to get the `distinct` `(b2, c2)` pairs by giving a value for `a1` I tried something like ``` a.find(:all, :joins => [:b, :c], :select => "b2, c2", :conditions => {:a => {:a1 => Time.now.midnight. ... Time.now}}, :group => "b2, c2") ``` The `SQL` that this produces works fine and I am able to see the results. But I think since I am doing a `a.find`, I am not able to retrieve `b2`, `c2` from the result set. How can I modify this so that I can get `b2` and `c2`?

Original source