title: sql query to laravel query with union
body: <p>I want to convert the below union query to laravel query </p>
  
  <pre><code>DB::select("select lead_master.lead_stage from lead_master inner join  user_master on 
  user_master.user_name=lead_master.assigned_user_name where region in (".$geo_string.") and teams 
  in (".$filter_teams_string.") group by (lead_stage) union
  select  meeting_hash from meetings_master where assigned_user_name in 
  (".$filter_username_string.") and meeting_hash in ('follow_up','first_time') group by 
  (meeting_hash) 
   union
   select sales_stage from opportunity_master where sales_stage in ('Identified','QO_to be 
   approved') and assigned_user in (".$filter_username_string.") group by (sales_stage)");
  </code></pre>
  
  <p>below query woeking fine in postgre</p>