title: Accessing join table (A table without model) in rails
body: <p>How to access the database table without the help of the model name?</p>
  
  <p>for example if we have model(Post model),</p>
  
  <pre><code>@instance_var=Post.find(params[:id])
  </code></pre>
  
  <p>how can I access the database table that has no model ?</p>