为什么修改信息后数据库表中内容为空
套用上一套修改课题的代码写了一个修改信息的代码，但是将内容修改提交后，再查询表中内容发现除了xuehao其他内容为空？
<?php<br />
//######################学生信息修改1##########################<br />
include "config.php";<br />
include "header.php";<br />
?> <br />
<title>修改学生信息</title><br />
<?php<br />
extract($_REQUEST); <br />
$query="update $student_table set name='$name1' where xuehao='$xuehao'";<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query);<br />
$query="update $student_table set sex='$sex1' where xuehao='$xuehao'";<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query);<br />
$query=mysql_query("update $student_table set class='$class1' where xuehao='$xuehao'");<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query);<br />
$query=mysql_query("update $student_table set password='$password2' where xuehao='$xuehao'");<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query);<br />
$query=mysql_query("update $student_table set password1='$password3' where xuehao='$xuehao'");<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query); <br />
$query="update $student_table set love='$love1' where xuehao='$xuehao'";<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query);<br />
$query="update $student_table set telephone='$telephone1' where xuehao='$xuehao'";<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query);<br />
$query="update $student_table set reward='$reward1' where xuehao='$xuehao'";<br />
mysql_query("set names 'GB2312'");<br />
$result=mysql_query($query);<br />
<br />
if($password2!=$password3)<br />
{<br />
echo"<p align=\"center\"><font color=\"#FF0000\"><b><big>输入的密码不一致，请重新输入。</big></b></font></p>";<br />
echo "<meta http-equiv=\"refresh\" content=\"2;url=alter_student1.php\">";<br />
exit;<br />
}<br />
<br />
if($result==true)<br />
{<br />
echo"<p align=\"center\"><font color=\"#FF0000\"><b><big>修改信息成功！</big></b></font>";<br />
echo "<meta http-equiv=\"refresh\" content=\"1;url=index.php\">";<br />
exit;<br />
}<br />
else<br />
{<br />
echo"<p align=\"center\"><font color=\"#FF0000\"><b><big>修改出错，请返回重新修改。</big></b></font></p>";<br />
echo "<meta http-equiv=\"refresh\" content=\"1;url=alter_student.php\">"; <br />
exit;<br />
}<br />
<br />
<br />
?><br />
<?php include "foot.php";?>
