session_start（）不能在线工作

Question

I'm having a problem to set a session for a user. it's working in my localhost but online it doesn't work.

I have a username called 's' and I have created a page to see what is the problem

here is the code. test.php

<?php 
session_start();
require 'connect.php';

$username = @$_POST['username'];

?>

<div class="center_body">
    <div class="search_field">
            <form method="POST" action="<?php echo $_SERVER['PHP_SELF']; ?>">
                <table border="0" width="100%" cellspacing="0" cellpadding="0">
                    <td align="left">username:</td>
                    <td align="right"><input type="text" name="username" class="search" /></td>
                </tr>

                </table>
                <input type="submit" value="log in" class="search" /></p>
            </form>
            </tr>

    </div>
</div>

<?php
$result = mysql_query("SELECT username FROM users WHERE username='$username'") or die(mysql_error);

    while($row = mysql_fetch_assoc($result))
    {
        $user = $row['username'];

    }

    if($username == $user)
    {
        echo '<div class="search_field"><b>you have logged successfully</b></div></ br>';
       $_SESSION['username'] = $username;

    }

    if(isset($_SESSION['username']))
    {
        echo $_SESSION['username'];
    }

?>  

like above code, it works, and also I can print the username. but when I edit the test.php to be

<?php 
session_start();
require 'connect.php';
    if(isset($_SESSION['username']))
    {
        echo $_SESSION['username'];
    }

?>  

now, this page should print username because I have successfully created the session. but it prints nothing so session seems not working

what do you thing is the problem?

EDIT: connect.php

<?php

$connect = @mysql_connect("localhost","root","") or die("error in connection");
$select  = @mysql_select_db("abc") or die ("no databse selected");

?>

of course I changed data to be connected to my host databas

Answer 1

try it:

if ($_SERVER['REQUEST_METHOD'] == 'POST'){
    $result = mysql_query("SELECT username FROM users WHERE username='$username' LIMIT 1") or die(mysql_error);
    while($row = mysql_fetch_assoc($result))
    {

        if($username == $row['username'])
        {
            echo '<div class="search_field"><b>you have logged successfully</b></div></ br>';
           $_SESSION['username'] = $username;
           break;

        }

    }    
}

Answer 2

ok guys as I thought it's from my host site.

the support tell me "I have set session.save_path for your account." and the problem is solved.

big thanks to you guys and especially for Danial :)

all the best to you :)