title: Adding merged array to PHP SQL output
body: <p>My Datatable talks to an SQL database through a php file. Unfortunately datatables doesn't allow for searching in two columns at the same time, but I'd like to go around that by adding a merged column to the json output of my php file.</p>
  
  <p>Here I'm adding <code>$arr</code> but it just says "Column not found":</p>
  
  <pre><code>$columns = array(
      array( 'db' =&gt; 'Author', 'dt' =&gt; 'authors'),
      array( 'db' =&gt; 'Editor', 'dt' =&gt; 'editor'),
      array( 'db' =&gt; 'Item Type', 'dt' =&gt; 'type'),
      array( 'db' =&gt; 'Publication Year',  'dt' =&gt; 'year' ),
      array( 'db' =&gt; 'Title',  'dt' =&gt; 'title' ),
      array( 'db' =&gt; 'Publication Title',  'dt' =&gt; 'pubtitle' ),
      array( 'db' =&gt; 'Publisher',  'dt' =&gt; 'publisher' ),
      array( 'db' =&gt; 'Url',  'dt' =&gt; 'url'),
      array( 'db' =&gt; 'DOI',  'dt' =&gt; 'doi' ),
      array( 'db' =&gt; 'Title',  'dt' =&gt; 'title' ),
      array( 'db' =&gt; 'Reviewed Author',  'dt' =&gt; 'reviewed' ),
      array( 'db' =&gt; 'Abstract Note',  'dt' =&gt; 'abstract' ),
      array( 'db' =&gt; 'ISBN',  'dt' =&gt; 'isbn' ),
      array( 'db' =&gt; 'Tags',  'dt' =&gt; 'tags'),
      array( 'db' =&gt; 'Place',  'dt' =&gt; 'place' ),
      array( 'db' =&gt; 'Type',  'dt' =&gt; 'genre' ),
      array( 'db' =&gt; 'Publisher',  'dt' =&gt; 'publisher' ),
      array( 'db' =&gt; 'Pages',  'dt' =&gt; 'pages' ),
      array( 'db' =&gt; 'Volume',  'dt' =&gt; 'volume' ),
      array( 'db' =&gt; 'Issue',  'dt' =&gt; 'issue')
  );
  
  $arr = array_merge($columns["authors"],$columns["editor"]);
  
  require( 'ssp.class.php' );
  
  echo json_encode(
      SSP::simple( $_GET, $sql_details, $table, $arr, $primaryKey, $columns)
  );
  </code></pre>