atk4\data\Reference_SQL_One::addField PHP Method

    public function addField($field, $their_field = null)
    {
        if (is_array($field)) {
            $defaults = $field;
            if (!isset($defaults[0])) {
                throw Exception('Field name must be specified', ['field' => $field]);
            }
            $field = $defaults[0];
        } else {
            $defaults = [];
        }
        if ($their_field === null) {
            $their_field = $field;
        }
        $e = $this->owner->addExpression($field, array_merge([function ($m) use($their_field) {
            return $m->refLink($this->link)->action('field', [$their_field]);
        }], $defaults));
        return $e;
    }