PHP量级数据遍历方案：yield生成器

getMessage();            exit();        }        static::$instance->setAttribute(\PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, false);    }    public static function getInstance()    {        if (!(static::$instance instanceof \PDO)) {            new static();        }        return static::$instance;    }    public static function excuteQuery(string $sql)    {        static::$sth = static::$instance->prepare($sql);        static::$sth->execute();    }    //防止实例被克隆    private function __clone()    {    }    public static function cursor()    {        while ($row = static::$sth->fetch(\PDO::FETCH_ASSOC)) {            yield $row;        }    }}DB::getInstance();DB::excuteQuery("select * from bill_info");foreach (DB::cursor() as $info) {    echo $info['id'] . PHP_EOL;}