Question

I want to update a MySQL database with an input form, essentially a settings page where a user can update/change their information. With this code below, the echo at the bottom runs and I’m not getting any errors, but the database isn’t updated. I tested it both on my local machine and on a server and it didn’t work with either, although I’m not sure that would have anything to do with it. $_SESSION['yourName'] is already set when the user logs in, so it will equal the current value in the database. I know there are tons of sql injection hole in here, but this is just a proof-of-concept code, not ready to go live. I tried running the query in phpMyAdmin and it worked fine.

PHP

if(isset($_POST['name']) || isset($_POST['password']) || isset($_POST['location']) || isset($_POST['img'])) {
 //put this in an external file for a little extra security
 $username = "my_username";
 $password = "my_password";
 $database = "database_name";
 $con = mysql_connect('localhost',$username,$password);
 if (!$con) {
    die('Oh poop.... Could not connect: ' . mysql_error());
 }
 //print item from database
 mysql_select_db($database, $con);

 if(isset($_POST['name'])) {
    $query = 'UPDATE users SET username=' . $_POST['name'] . 'WHERE username=' . $_SESSION['yourName'];
    mysql_query($query);
    $_SESSION['yourName'] = $_POST['name'];
 }
 if(isset($_POST['password'])) {
    $query = 'UPDATE users SET password=' . $_POST['password'] . 'WHERE username=' . $_SESSION['yourName'];
    mysql_query($query);
 }
 if(isset($_POST['location'])) {
    $query = 'UPDATE users SET location=' . $_POST['location'] . 'WHERE username=' . $_SESSION['yourName'];
    mysql_query($query);
    $_SESSION['location'] = $_POST['location'];
 }
 if(isset($_POST['img'])) {
    $query = 'UPDATE users SET img=' . $_POST['img'] . 'WHERE username=' . $_SESSION['yourName'];
    mysql_query($query);
    $_SESSION['img'] = $_POST['img'];
 }
 echo '<script type="text/javascript">alert("changes saved")</script>';
}

HTML

<form method="post">
    new name: <input type="text" name="name" /><br />
    new password: <input type="text" name="password" /><br />
    new location: <input type="text" name="location" /><br />
    new img: <input type="text" name="img" /><br />
    <input type='submit' name='save' value='save' />
    <input type='submit' name='logout' value='logout' />
</form>

Answer 1

try to modify you php statement by using double quotes instead of single quotes.

$query = "UPDATE users SET username='" . $_POST['name'] . "' WHERE username= '" . $_SESSION['yourName'] . "'";

but the query above is vulnerable with SQL Injection, please read the article below,

• How to prevent SQL injection in PHP?