php求和

Question

我的源代码是
body background=guo.JPG>
<?php
$con1=mysql_connect("localhost","guo","guo");
if($con1)
mysql_select_db("guo",$con1);
$a2="select * from jiesuan";
$a3=mysql_query($a2,$con1);
$a4=mysql_num_rows($a3);
echo "当前共有 $a4 条数据记录<br>";
echo "<table width=95% border=2 align=center>";
echo "<tr>";
echo "<th>序号</th>";
echo "<th>用途</th>";
echo "<th>金额</th>";
echo "<th>时间</th>";
echo "</tr>";
while ($a5=mysql_fetch_array($a3))
{
echo "<tr>";
echo "<td>".$a5["xh"]."</td>";
echo "<td>".$a5["yt"]."</td>";
echo "<td>".$a5["sl"]."</td>";
echo "<td>".$a5["sj"]."</td>";
echo "</tr>";
}
mysql_close($con1);
?>
</body>
</html>
现在我想将SL的和求出来，改怎么写啊

Answer 1

$total = 0;
while ($a5=mysql_fetch_array($a3))
{
echo "<tr>";
echo "<td>".$a5["xh"]."</td>";
echo "<td>".$a5["yt"]."</td>";
echo "<td>".$a5["sl"]."</td>";
echo "<td>".$a5["sj"]."</td>";
echo "</tr>";
$total += $a5['sl'];
}
echo $total;