title: How to combine multiple scopes with OR
body: <p>Rails 6</p>
  <p>I have three scopes</p>
  <pre><code>scope :a, -&gt; { where(&quot;first_name like 'A%'&quot;) }
  scope :b, -&gt; { where(&quot;first_name like 'B%'&quot;) }
  scope :c, -&gt; { where(&quot;first_name in ('Charles','Chris')&quot;) }
  </code></pre>
  <p>I want to merge these three scopes and create a new scope like</p>
  <pre><code>scope :combined_abc, -&gt; { where(&quot;first_name like 'A%'&quot;) or 
                            where(&quot;first_name like 'B%'&quot;) or 
                            where(&quot;first_name in ('Charles','Chris')&quot;) 
                          }
  </code></pre>
  <p>I am looking for a clean and nice way to pre-define the big scope rather than using three OR conditions in the SQL.</p>
  <p>My ultimate goal is to delete the users whose first names start with &quot;a&quot;, &quot;b&quot; or first name is 'Charles' or 'Chris'.</p>
  <p><code>user.combined_abc.destory_all</code></p>