title: Objection js update with increments +1
body: <p>How i can update value in database using objection ?
  My SQL query works perfect. </p>
  
  <pre><code>UPDATE "freePlace"
  SET number = number-1
  WHERE   date &gt;= '2017-10-20'   AND date &lt;= '2017-10-30' AND "idObject" = '1'
  </code></pre>
  
  <p>My objection code:</p>
  
  <pre><code>FreePlace.query().patch({number:number+1}).where('date', '&gt;=', startDate)
    .andWhere('date', '&lt;=', endDate)
    .andWhere('idParking', '=', parkingId)
  </code></pre>
  
  <p>Problem is in patch({number:number+1}) 
  how i need do this ? </p>