php - session 变量未从 php 的下拉菜单中存储

Question

我已经查找了许多不同的存储 session 变量的方法，但似乎无法找到为什么我的 session 变量没有从下拉菜单中存储。这是我的 Campaign_select.php 代码，然后在按下提交按钮后转到 store_select.php。

    <?php
    session_start ();
    $host="localhost"; // Host name 
    $username="sxx2"; // Mysql username 
    $password="xxxxx!"; // Mysql password 
    $db_name="sxxxxx"; // Database name 
    $tbl_name="campaign"; // Table name 

    // Connect to server and select databse.
    mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
    mysql_select_db("$db_name")or die("cannot select DB");

    $query = "SELECT campaignname FROM campaign";
    $result = mysql_query($query) or die(mysql_error());

    while($row = mysql_fetch_assoc($result))
    {
    $dd .= "<option value='{$row['campaignID']}'>{$row['campaignname']}</option>";
    } 
    if ($_POST['Submit']) 
    {

    if(isset($_POST['campaignname']))
    {   
    $_SESSION['campaign']=$_POST['campaignName'];
    }
    } 
    $_SESSION['test']="bye";
    ?>

    <form action="store_select.php" method="post">
    <select name="campaignName" id="campaignname"><? echo $dd; ?></select>
<input name="Submit" type="submit" value="Submit">
</form>

这是 store_select.php:

<?php
session_start();
$host="localhost"; // Host name 
$username="sxxxx2"; // Mysql username 
$password="Wxxxx1!"; // Mysql password 
$db_name="xxxx2"; // Database name 
$tbl_name="users"; // Table name 

// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");

$campaign=$_SESSION['campaign'];
echo $_SESSION['campaign'];
echo $_SESSION['test'];

$query = "SELECT storename FROM stores WHERE campaignname='$campaign'";
$result = mysql_query($query) or die(mysql_error());


while($row = mysql_fetch_assoc($result))
{
    $dd .= "<option value='{$row['storeID']}'>{$row['storename']}</option>";
} 
?>
<form action="" method="post">
<select name="stores"><? echo $dd; ?></select>
</form>

Answer 1

替换

<form action="store_select.php" method="post">

与

<form action="" method="post">

和

if(isset($_POST['campaignname']))

与

if(isset($_POST['campaignName']))