public function getQualifiedForeignKey()
    {
        if (is_array($this->foreignKey)) { //Check for multi-columns relationship
            return array_map(function ($k) {
                return $this->child->getTable().'.'.$k;
            }, $this->foreignKey);
        } else {
            return $this->child->getTable().'.'.$this->foreignKey;
        }
    }