sql - How to group by a range of values in ActiveRecord (ruby on

How to group by a range of values in ActiveRecord (ruby on rails)?

I have an ActiveRecord model that has two columns I want to group and sum by (both are integers). The issue I can't seem to solve is how to sum the first column as a group of the second column, with the second column being grouped by a range. I know that I can do Model.sum(:first_column, group: :second_column), but this results in many groups, because the second columns values are spread out. How can I group the second columns' values, e.g. in ranges of 10 (0-9, 10-19, 20-29, etc.)?

Full article: http://stackoverflow.com/questions/13428409/how-to-group-...