Check out the FREE chatroom mod for IPB 3.x

<input type="hidden" name="redirect" value="http://">

<?php
$dbhost = 'localhost';
$dbuser = 'username';
$dbpass = 'password';

$conn = mysql_connect($dbhost, $dbuser, $dbpass) or die                      ('Error connecting to mysql');

$dbname = 'databasename';
mysql_select_db($dbname);
?>

<?php if (isset($_COOKIE["member_id"])) {
    if ($_COOKIE["member_id"] == 0) {

echo "<form action='/board/index.php?act=Login&amp;CODE=01' method='post' name='LOGIN'>
<strong>Username</strong>: <input type='text' size='25' maxlength='64' name='UserName' /><br />
<strong>Password</strong>: <input type='password' size='25' name='PassWord' /><br />
Remember Me? <input class='checkbox' type='checkbox' name='CookieDate' value='1' checked='checked' /><br />
<input class='button' type='submit' name='submit' value='Log In' />
</form><br />
<a href='/board/index.php?act=Reg'>Register</a>";
    }
    else { // Content that shows up if logged in
// get the persons username from the database
$query = mysql_query("SELECT `members_display_name` FROM `ibf_members` WHERE `id`=" . mysql_real_escape_string($_COOKIE['member_id']) . " LIMIT 1");

//then you need to get the result into an array
$result = mysql_fetch_assoc($query);

//show the username
echo "Welcome Back {$result['members_display_name']}";
    }
}
else {

echo "<form action='/board/index.php?act=Login&amp;CODE=01' method='post' name='LOGIN' target='_top'>
<strong>Username</strong>: <input type='text' size='25' maxlength='64' name='UserName' /><br />
<strong>Password</strong>: <input type='password' size='25' name='PassWord' /><br />
Remember Me? <input class='checkbox' type='checkbox' name='CookieDate' value='1' checked='checked' /><br />
<input class='button' type='submit' name='submit' value='Log In' />
</form><br />
<a href='/board/index.php?act=Reg'>Become a Member!</a>";
} ?>

    else { // Content that shows up if logged in
echo "Welcome {members_display_name}!";
    }