title: Rails: update multiple attributes without validation, 1 sql transaction
body: <p>I know that in Rails you can call <code>model.update_attribute :foo, 'bar'</code> and it will update just that one attribute in the db without validating the rest of the model. This causes one SQL transaction.</p>
  
  <p>You can also set multiple attributes with <code>.update_attributes</code>, but this cannot skip validations.</p>
  
  <p>Or, you can call <code>.save( :validate=&gt;false )</code> and update the model without validation. However, this saves all the attributes on the model in their current state, rather than being able to limit this to certain columns.</p>
  
  <p>My question is, is there any way to set more than one value on a model, but not all of them, without triggering validations, in a single SQL transaction?</p>