如何修改数据库中内容
运行这段代码时存在一定问题，如图。

<?php
//######################修改课题界面3##########################
  include "config.php";
  include "admin_header.php";
?> 
<title>修改课题</title>
<?php
   $query="update $jiaoshi_table set subject='$subject1' where id='$id'";
   mysql_query("set names 'GB2312'");
   $result=mysql_query($query);
   $query="update $jiaoshi_table set teacher='$teacher1' where id='$id'";
   mysql_query("set names 'GB2312'");
   $result=mysql_query($query);
   $query=mysql_query("update $jiaoshi_table set zhicheng='$zhicheng1' where id='$id'");
   mysql_query("set names 'GB2312'");
   $result=mysql_query($query);
   $query=mysql_query("update $jiaoshi_table set specialized='$specialized1' where id='$id'");
   mysql_query("set names 'GB2312'");
   $result=mysql_query($query);
   $query=mysql_query("update $jiaoshi_table set code='$select' where id='$id'");
   mysql_query("set names 'GB2312'");
   $result=mysql_query($query); 
   $query="update $jiaoshi_table set beizhu='$introduction' where id='$id'";
   mysql_query("set names 'GB2312'");
   $result=mysql_query($query);
   
   $query="select number as sn,surplus as ssn from $jiaoshi_table where id='$id'";
mysql_query("set names 'GB2312'");
$result=mysql_query($query);
$row=mysql_fetch_array($result);
if($number1<$row[sn])
{
if($number1<($row[sn]-$row[ssn]))
{
echo"<p align=\"center\"><font color=\"#FF0000\"><b><big>人数不能少于现已选题人数，人数列修改失败！</big></b></font>";
echo"<meta http-equiv=\"refresh\" content=\"2;url=alter_keti.php\">";
exit;
}
else
{
    $query2=mysql_query("update $jiaoshi_table set number='$number1' where id='$id'");
$query3=mysql_query("update $jiaoshi_table set surplus=surplus-($row[sn]-$number1) where id='$id'");
mysql_query("set names 'GB2312'");
   $result1=mysql_query($query3);

}
}
else
{
$query4=mysql_query("update $jiaoshi_table set number='$number1' where id='$id'");
$query5=mysql_query("update $jiaoshi_table set surplus=surplus+($number1-$row[sn]) where id='$id'");
mysql_query("set names 'GB2312'");
   $result2=mysql_query($query5);

   }

if($result==true)
{
   echo"<p align=\"center\"><font color=\"#FF0000\"><b><big>修改课题成功！</big></b></font>";
   echo "<meta http-equiv=\"refresh\" content=\"1;url=alter_keti.php\">";
   exit;
 }
 else
 {
   echo"<p align=\"center\"><font color=\"#FF0000\"><b><big>修改出错，请返回重新修改</big></b></font></p>";
   echo "<meta http-equiv=\"refresh\" content=\"1;url=alter_keti.php\">"; 
   exit; 
 
 }

?>

<?php include "foot.php";?>

[解决办法]
你贴出的代码的第 7、8 行不是这样吗
<?php
$query="update $jiaoshi_table set subject='$subject1' where id='$id'";
把他改成这样
<?php
extract($_REQUEST); //加上这句
$query="update $jiaoshi_table set subject='$subject1' where id='$id'";

就可以了，其他都不要动
以后遇到类似的情况都这样做