title: jOOQ: convert Field in select statement from type1 to type2
body: <p>I have a statement like this:</p>
  
  <pre><code>SelectSelectStep&lt;Record14&lt;
      String, String, String, Timestamp, String, String, String, Integer, 
      Timestamp, String, String, String, Integer, DayToSecond&gt;&gt; select = create.select(
      TECHNICAL_WORK.NUMBER, TECHNICAL_CODE.CODE, TECHNICAL_CODE.DESCRIPTION,
      twLog.START_TIME, twStartLog.CODE, twStartLog.FIRST_NAME, twStartLog.LAST_NAME, twStartLog.CATEGORY,
      twLog.STOP_TIME, twEndLog.CODE, twEndLog.FIRST_NAME, twEndLog.LAST_NAME, twEndLog.CATEGORY,
      DSL.timestampDiff(twLog.STOP_TIME, twLog.START_TIME)
  );
  </code></pre>
  
  <p>the last field is of type <code>Field&lt;DayToSecond&gt;</code> and I need to convert it to <code>Field&lt;Double&gt;</code> using DayToSecond.totalMinutes()</p>
  
  <p>I can't find an api like this, eg:</p>
  
  <pre><code>DSL.timestampDiff(twLog.STOP_TIME, twLog.START_TIME).map( from -&gt; from.totalMinutes() )
  </code></pre>
  
  <p>Can I do this conversion somehow? </p>