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This becomes more clear with
our example, so let??™s define our farmer model and show the association in action:
class Farmer < ActiveRecord::Base
has_many :cows
end
CHAPTER 4 ?–  CORE FEATURES OF ACTIVE RECORD 71
The has_many association returns an array of objects from the table containing the matching
foreign key from the table specified. Again, walking through a plain English version makes
this easier to understand, so let??™s use this association as follows: get a list of the cows a given
farmer owns.
Here, we are starting with the farmer table??”we know the farmer we want information about,
and we want to get a list of cows that this farmer owns. This is really a lot like our belongs_to
example, in that we just want to join the two tables together based on farmer_id. However,
this time, we are starting in the farmer table with just the farmer ID. With SQL, our inner join
would look like the following:
# this is the T-SQL version (MS SQL Server uses T-SQL)
cowlist = Farmer.find_by_sql(["Select cows.name as cowname from
farmer inner join cows on farmer.


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