update (edit) user in php

im a newbie in php and sql programming and can someone help me in my syntax , lately ive been creating this code to edit my user and write it on the database but it always gets an error in oldpassword and password , and it always says password didnt match even if i do it correctly the process , any help on me ? tnx

<?php

$update = strip_tags($_POST['update']); 

$username = strtolower(strip_tags($_POST['username']));

$oldpassword = strip_tags($_POST['oldpassword']);

$newpassword = strip_tags($_POST['newpassword']);

$firstname = strip_tags($_POST['first']);

$lastname = strip_tags($_POST['last']);

$gender = strip_tags($_POST['gender']);

$address = strip_tags($_POST['address']);

$zipcode = strip_tags($_POST['zip']);

$contact = strip_tags($_POST['con']);

$email = strip_tags($_POST['mail']);

error_reporting(0);



if($update)
{




if($username&& $oldpassword && $newpassword && $firstname && $lastname && $address && $zipcode && $contact && $email)
{

    $connect = mysql_connect("localhost","root","") or die(mysql_error());
    mysql_select_db("brightlights") or die(mysql_error());

    $updatecheck = mysql_query("SELECT * FROM username FROM tb_user WHERE username='$username'");
    $count = mysql_num_rows($updatecheck);
    if($count<=1)
    {

    if($_SESSION['password']==($oldpassword))
    {

    mysql_query("UPDATE tb_user SET
                    username = '$username',
                    password = '$newpassword',
                    Firstname = '$firstname',
                    Lastname = '$lastname',
                    gender = '$gender',
                    address = '$address',
                    zipcode = '$zipcode',
                    contact = '$contact',
                    email = '$email'
                    WHERE username='".$_SESSION['username']."'");
                    $_SESSION['username'] = $username;
                    $_SESSION['password'] = $newpassword;
              开发者_JS百科      $_SESSION['Firstname'] = $firstname;
                    $_SESSION['Lastname'] = $lastname;
                    $_SESSION['gender'] = $gender;
                    $_SESSION['address'] = $address;
                    $_SESSION['zipcode'] = $zipcode;
                    $_SESSION['contact'] = $contact;
                    $_SESSION['email'] = $email;
                    session_write_close();
                    echo "Succesfully Updated!";

                }else
                    echo "Password not match!";
            }else
                echo "Username already Taken!";
        }else
            echo "Please fill up all form!";
}
?>

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  if($_SESSION['password']==($oldpassword))

But I can't see session_start() after <?php

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I think $_SESSION['password'] is an encrypted password that doesn't match. Please echo $_SESSION['password'] and $oldpassword and exit, and check their values.