查询在收货时将两个相同的产品打印为单个产品？

I am developing point of sale in php.I have two different sales . I sold 4 mobiles in first sale and sold 2 mobiles in second sale.The following query prints 2 items on receipt.But i want to display only one item(mobile) with quantity 6??

<?php
$result = $db->query("SELECT * FROM stock_sales where date BETWEEN '$fromdate' AND '$todate' ");

while ($line = $db->fetchNextObject($result)) {
?>

<tr> 
<td><?php echo $line->stock_name; ?><
<td><?php echo $line->quantity; ?></td>
</tr>}

</div>

Modify your query to be

SELECT stock_name, count(*), sum(quantity) AS sum_quantity FROM stock_sales where date BETWEEN '$fromdate' AND '$todate' group by stock_name