src/Model/Tables/MelisPageHistoricTable.php
public function getPageHistoricListOfActions($order = 'ASC')
    {
        $select = $this->tableGateway->getSql()->select();
        $select->columns(["action" => new Expression('DISTINCT(hist_action)')]);
        $select->order('hist_action' . ' '  . $order);
        $resultSet = $this->tableGateway->selectWith($select);

        return $resultSet;
    }
public function getPageHistoricListOfActions($order = 'ASC')
    {
        $select = $this->tableGateway->getSql()->select();
        $select->columns(["action" => new Expression('DISTINCT(hist_action)')]);
        $select->order('hist_action' . ' '  . $order);
        $resultSet = $this->tableGateway->selectWith($select);

        return $resultSet;
    }
This will return all distinct actions
@param string $order
@return mixed