The expressions to SELECT as virtual fields.
Type: array
protected $expressions = array();
© 2001–2016 by the original authors
Licensed under the GNU General Public License, version 2 and later.
Drupal is a registered trademark of Dries Buytaert.
https://api.drupal.org/api/drupal/core!lib!Drupal!Core!Database!Query!Select.php/property/Select::expressions/8.1.x