Cakephp 3同一表的2列总和

// src/Model/Table/UsersTable.php

namespace App\Model\Table;

use Cake\ORM\Table;

class UsersTable extends Table
{
    public function initialize(array $config)
    {
        $this->hasMany('UserColumns', [
            'className' => 'UserColumns',
            'foreignKey' => 'user_id'
        ]);
    }
}

// src/Controller/UsersController.php

namespace App\Controller;

use App\Controller\AppController;

class UsersController extends AppController
{
    public function sum()
    {
        $this->loadModel('UserColumns');

        $query = $this->UserColumns->find();
        $query->select(['total' => $query->func()->sum('column1 + column2')]);

        $result = $query->first();

        $sum = $result->total;

        $this->set(compact('sum'));
    }
}