title: Rails 3 + activerecord, the best way to "mass update" a single field for all the records that meet a condition
body: <p>In rails 3, using activerecord, is there a single-query way to set the <strong>:hidden</strong> field to <strong>TRUE</strong> for all records that meet a condition ... say, for example, <code>:condition =&gt; [ "phonenum = ?", some_phone_number ]</code></p>
  
  <p>If a single query cannot do it, what IS the optimal approach?</p>