Rails 3 query on condition of an association's count

Question

In Rails 3 with mysql, suppose I have two models, Customers and Purchases, obviously purchase belongs_to customer. I want to find all the customers with 2 orders or more. I

Answer 1

No need to install a gem to get this to work (though metawhere is cool)

Customer.joins(:purchases).group("customers.id").having("count(purchases.id) > ?",0)