title: How to concat two columns
body: <p>I need to concat two columns <code>firstname</code> and <code>lastname</code> as name in a crosstab select, example:</p>
  
  <pre><code>select * from crosstab('SELECT concat(u.firstname," ",u.lastname)as name
  </code></pre>
  
  <p>But I get this error:</p>
  
  <pre><code>column  « » doesn't exist.
  </code></pre>
  
  <p>How can I do it?</p>