关于退选课程的代码,系统提示未定义变量。
退选课程提交后,系统提示错误,第15、35、38行有未定义的变量“xuehao” 请问我应该怎么修改?
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><br />
<html xmlns="http://www.w3.org/1999/xhtml"><br />
<head><br />
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><br />
<title>退选课题</title><br />
</head><br />
<br />
<body><br />
<?php <br />
//######################退选课题界面3##########################<br />
include "config.php";<br />
include "header.php";?><br />
<?php<br />
extract($_POST);<br />
$query="select * from $student_table where xuehao='".$xuehao."'";<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query);<br />
$row=mysql_fetch_array($result);<br />
$id=$row['id'];<br />
<br />
$query1="select number as sn,surplus as ssn from $jiaoshi_table where id='$id'";<br />
mysql_query("set names 'GB2312'");<br />
$result1=mysql_query($query1);<br />
$row1=mysql_fetch_array($result1);<br />
if($row1['sn']==1)<br />
{<br />
$query2=mysql_query("update $jiaoshi_table set xuehao='未选' where id='$id'");<br />
$query3=mysql_query("update $jiaoshi_table set surplus=surplus+1 where id='$id'");<br />
}<br />
else<br />
{<br />
if(($row1['sn']-$row1['ssn'])==1)<br />
$query7=mysql_query("update $jiaoshi_table set xuehao='未选' where id='$id'");<br />
else<br />
$query6=mysql_query("update $jiaoshi_table set xuehao=replace(xuehao,concat('".$xuehao."','\n'),'') where id='$id'");<br />
$query8=mysql_query("update $jiaoshi_table set surplus=surplus+1 where id='$id'");<br />
<br />
$query5="update $student_table set id=0 where xuehao='".$xuehao."'";<br />
mysql_query("set names 'GB2312'");<br />
$result5=mysql_query($query5);<br />
if($result5==true)<br />
{<br />
echo"<p align=\"center\"><font color=\"#FF0000\"><b><big>退选课题成功!</big></b></font>";<br />
echo "<meta http-equiv=\"refresh\" content=\"2;url=back_keti.php\">";<br />
exit;<br />
}<br />
else<br />
{<br />
echo"<p align=\"center\"><font color=\"#FF0000\"><b><big>退选出错,请返回重新退选</big></b></font></p>";<br />
echo "<meta http-equiv=\"refresh\" content=\"1;url=back_keti.php\">"; <br />
exit;<br />
}<br />
}<br />
<br />
?><br />
<?php include "foot.php";?><br />
</body><br />
</html>
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