Select, group and sum results from database

Question

I have a database with some fields I'd like to sum. But that's not the big problem, I want to group those fields by the month they were created. ActiveRecord automaticaly created a field named "created_at". So my question; how can I group the result by month, then sum the fields for each month?

Updated with code

@hours = Hour.all(:conditions => "user_id = "+ @user.id.to_s, 
                  :group => "strftime('%m', created_at)",
                  :order => 'created_at DESC')

This is the code I have now. Managed to group by month, but doesn't manage to sum two of my fields, "mins" and "salary" which I need to sum

Answer 1

You can use active record calculations to do this. Some example code might be

Model.sum(:column_name, :group => 'MONTH("created_at")')

Obviously with the caveat MONTH is mysql specific, so if you were developing on an SQLite database this would not work.