php中变量的使用问题
从数据库中获得了各区的销售金额和销售数量，要对数量和金额求和。代码如下：
<br>
<?PHP<br>
<br>
ob_start();<br>
require_once 'DB.php';<br>
ob_end_clean();<br>
$db=DB::Connect();<br>
$result=$db->QueryLastMonth();<br>
$result1=$db->QueryLastMonthByArea();<br>
$all_sales_amount;<br>
$all_sales_money;<br>
echo 'begin '.$all_sales_amount;<br>
while($row1= sybase_fetch_assoc($result1))<br>
{<br>
?><br>
<tr><br>
<th data-options="field:'itemid',width:80"><?php <br>
switch($row1["areacode"]){<br>
case "E":<br>
echo "华东区";<br>
break;<br>
case "C":<br>
echo "东北区";<br>
break;<br>
case "N":<br>
echo "华北区";<br>
break;<br>
case "W":<br>
echo "西大区(W)";<br>
break;<br>
case "H":<br>
echo "华中区";<br>
break;<br>
case "S":<br>
echo "华南区";<br>
break;<br>
case "F":<br>
echo "华东区(经销)";<br>
break;<br>
case "T":<br>
echo "西大区(T)";<br>
break;<br>
}<br>
?></th><br>
<th data-options="field:'productid',width:80"><?php echo $row1["area_salesgoodssum"]?></th><br>
<th data-options="field:'listprice',width:100,align:'right'"><?php echo $row1["area_salesmoneysum"]?></th><br>
<th data-options="field:'unitcost',width:80,align:'right'">--</th><br>
<th data-options="field:'status',width:60,align:'center'">--</th><br>
</tr><br>
<br>
<?php <br>
$all_sales_amount+=$row1["area_salesgoodssum"];<br>
$all_sales_money+=$row1["area_salesmoney"];<br>
echo '循环中数量'.$all_sales_amount."金额".$all_sales_money."<br>";<br>
}<br>
?><br>
</thead><br>
</table><br>
</div><br>
<br>
<br>
<div class="easyui-draggable" data-options="handle:'#title'" style="width:220px;height:160px;background:#fafafa;border:1px solid #ccc;margin-top:10px"><br>
<div id="title" style="padding:5px;background:#ccc;color:#FA0000">销售简报<?php ?></div><br>
<span>总金额：<?php echo $all_sales_money; ?> </span><br><br>
<span>总数量：<?php echo $all_sales_amount?> </span><br>
$all_sales_amount为销售数量，$all_sales_money为销售金额。但运行的结果销售数量计算出的结果是错误的，销售金额总是为0（如下）请问上面的代码出了什么问题？
