title: Remove "Select * from dual" from UNION in JOOQ
body: <p>Here's the code:</p>
  
  <pre><code>SelectQuery&lt;Record&gt; resultQuery = dslContext.selectQuery();
  for(int floor : floors) {
      method1(resultQuery,floor);
  }
  </code></pre>
  
  <p>And then:</p>
  
  <pre><code>method1(SelectQuery&lt;Record&gt; resultQuery,int floor){
      SelectQuery&lt;Record&gt; query = dslContext.selectQuery();
      /*
       Now I am creating subqueries for parameter floor by adding condition 
       in above created query 
      */
  
      resultQuery.union(query);
  }
  </code></pre>
  
  <p>Issue is that in final query(resultQuery)  I am getting "Select * from dual" appended. It is adding because I created "resultQuery" as empty.</p>
  
  <p>Is there any way I can replace or remove "Select * from dual" from final query.</p>
  
  <p>Thanks</p>