title: Select multiple options in a collection_select rails
body: <p>I know how to put together a simple select box that takes its values from a model</p>
  
  <pre><code>&lt;%= f.collection_select(:sector_id, Sector.all, :id, :name, :prompt =&gt; "Please Select a Sector") %&gt;
  </code></pre>
  
  <p>My question is how do i allow a user to select multiple options and then store them in the model. I know i need to use</p>
  
  <pre><code>:multiple =&gt; true
  </code></pre>
  
  <p>But unsure on the syntax</p>
  
  <p>Usually for multiple entries to a model i would use accepts_nested_attributes_for but am i correct in thinking i don't need to for this example?</p>
  
  <p>Thanks</p>