title: How to concat columns in bookshelf.js?
body: <p>Trying to select columns with bookshelf and concat ids. My db is postgresql. In knex, I do it like this:</p>
  
  <pre><code>knex('client_users')
      .select(
          'client_user_id as id',
          'status',
          'email',
          'last_login_date as lastLoginDate',
          knex.raw(`CONCAT(first_name, ' ', last_name) as "displayName"`)
      )
      .whereIn('client_user_id', clientUserIds)
      .andWhere('status', 'pending')
      .tap(clientUsers =&gt; console.log('clientUsers retrieved:', clientUsers));
  </code></pre>
  
  <p>It does the job and returns:</p>
  
  <pre><code>[{
      id: 1, 
      status: 'pending', 
      email: 'pennywise@derry.com, 
      lastLoginDate: [Date Object], 
      displayName: 'John Smith'}, 
      {...}, {...}, etc]
  </code></pre>
  
  <p>The docs aren't clear and I see in the docs they have select, but nothing about what params it needs or how to do what I want :(</p>