开发学到的东西
1.
options = User.all(:conditions => "status <> 3", :order => "firstname, lastname").collect{|x| [x.name, x.id.to_s]}
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cars = Car.where(:colour => 'black').all ? (adding .all means it will load the data with no waiting.)
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cars = Car.find(1)
cars = Car.find(params[:id])
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cars = Car.order('created_at ASC')
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oldest_car = cars.first
newest_car = ?cars.last
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