EllisLab/CodeIgniter — pull request #847 by WanWizard (2011-12-28 13:09:59+00:00)
Title: added query grouping to Active Record

this is a feature that has been lacking for a very long time. lots of people complained
about it over the years, but it never got added so you'd have to resort to handcrafted
queries when you needed this feature.

This is a port of code from DataMapper, in use since CI 1.6.