title: boost featured results in relevance sorted sql
body: <p>I have a DB table of jobs. The table has a column 'featured' = NULL or 1.</p>
  
  <p>A user can search the table using keywords. And I sort them by relevancy, date, or salary, like below (relevancy):</p>
  
  <pre><code>SELECT SQL_CALC_FOUND_ROWS *, MATCH(`title`) 
              AGAINST ("*'.$keywords.'*") 
              AS Relevance 
              FROM jobs2 
              WHERE MATCH(`title`) 
              AGAINST ("*'.$keywords.'*") 
              ORDER BY Relevance
              LIMIT 0,50
  </code></pre>
  
  <p>I want any jobs that are 'featured' to be first on each page (but each featured job still in order themselves).</p>
  
  <p>e.g if a natural search was to return (in order):</p>
  
  <pre><code>Job1  not featured
  Job2  not featured
  Job3  featured
  Job4  not featured
  Job5  featured
  </code></pre>
  
  <p>I want featured jobs at the top in order like:</p>
  
  <pre><code>Job3  featured
  Job5  featured
  Job1  not featured
  Job2  not featured
  Job4  not featured
  </code></pre>
  
  <p>How can I achieve this? Ideally in the SQL query itself if possible</p>