如何从mysql数据库中获取今天的总数据和

我需要得到今天到期的销售。总销售行"total"，总付款行"payed"。我需要得到今天的全部到期。

$sql = "SELECT id, SUM(total) AS total, SUM(paid) AS paid FROM sma_sales WHERE DATE(`timestamp`) = CURDATE()";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc())
    {
        echo $sum = $row['total'] - $sum = $row['paid'];
    }
} else {
    echo "0.00 results";
}

我得到结果0.00我需要查看今天的总"到期销售"金额结果。数据库表屏幕截图

请帮忙。