Sorting with related tables

I have two tables: users and tickets. A user has many tickets which is
defined in the model. I want to order the users based on the number of
tickets they have. What is the easiest way to do it in Rails without
writing to many SQL statements.

Look at adding a "counter cache" column to your User model to store
the amount of tickets associated to them. Then you can just use that
column to sort by in a normal find.