title: Storing the login time in a mysql database
body: <p>I'm trying to store login time in a mysql database.
  What I want is..that when a user logs in..the script should store the current time in the table "user" having a column "last_seen".
  last_seen is of DATETIME datatype.</p>
  
  <p>Here's the code I've written(it's a little part of a login script..it works after the user has enter the username and password, and they are matched in the database. :-</p>
  
  <pre><code>$_SESSION['username']=$username;
  $_SESSION['logged']=1;
  $date = date('Y-m-d H:i:s');
  $query = "INSERT INTO user
            (last_seen)
            VALUES
            ('" . $date . "')
            WHERE user_name = '" . $username . "'";
           mysql_query($query, $db) or die (mysql_error($db));
  header('Refresh: 5; URL = main.php');
  echo "Login successful, redirecting...";
  die();
  </code></pre>
  
  <p>This throws me the error :- 
  You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE user_name = 'test'' at line 5
  (The username of the account from which I'm logging in is :- test)</p>
  
  <p>What do I change so the code works ?The code would store the login time of the user in the db(which would be later accessed at a backend page).</p>