SQL同一个表，PHP分别查询2列数据的总和然后输出

<code><span>$query_num</span> = <span>"SELECT SUM(order_num) from hcf_order_db where order_id = XXX"</span>;
<span>$arr_qn</span> = mysqli_query(<span>$dbc</span>,<span>$query_num</span>);
<span>list</span>(<span>$sum</span>)=mysqli_fetch_row(<span>$arr_qn</span>);</code>

<code><span>$query_amount</span> = <span>"SELECT SUM(order_amount) from hcf_order_db where order_id = XXX"</span>;
<span>$arr_qm</span> = mysqli_query(<span>$dbc</span>,<span>$query_amount</span>);
<span>list</span>(<span>$sum2</span>)=mysqli_fetch_row(<span>$arr_qm</span>);</code>

<code><span><<span>td</span><span>class</span>=<span>'font-songti'</span><span>align</span>=<span>'center'</span>></span><span><span><?php</span><span>echo</span><span>$sum</span><span>?></span></span><span></<span>td</span>></span><span><<span>td</span><span>class</span>=<span>'font-cali'</span><span>align</span>=<span>'right'</span>></span><span><span><?php</span><span>echo</span><span>$sum2</span><span>?></span></span><span></<span>td</span>></span></code>