title: Concatenate (glue) where conditions by OR or AND (Arel, Rails3)
body: <p>I have several <strong>complex</strong> queries (using subqueries, etc...) and want to glue them together with OR or AND statement.</p>
  
  <p>For example:</p>
  
  <pre><code>where1=table.where(...)
  where2=table.where(...)
  </code></pre>
  
  <p>I would like something like</p>
  
  <pre><code>where3=where1.or where2
  </code></pre>
  
  <p>Next example doesn't work for me:</p>
  
  <pre><code>users.where(users[:name].eq('bob').or(users[:age].lt(25)))
  </code></pre>
  
  <p>because of I have several where(..) queries and I want to concatenate <em>them</em>.</p>
  
  <p><strong>In other words</strong></p>
  
  <p>I have 3 methods: first return first where, second-second, third - OR concatenation. </p>
  
  <p>I must have able to use <em>all 3 methods</em> in my application and save <strong>DRY</strong> code</p>