title: Apache Spark - Adding two columns
body: <p>Is there a way to add two columns so that the first one is a date and the second one contains the number of days that need to be added? I'm trying</p>
  
  <pre><code>date_add(res.col("date"), res.col("days"));
  </code></pre>
  
  <p>But this doesn't work, since <code>date_add()</code> requires a <code>Column</code> and an <code>int</code>, while I have two columns.</p>
  
  <p>Thank you!</p>