Re: Login Script: mysql_num_rows(): supplied argument is not a valid MySQL result resource

--- On Fri, 2/19/10, Ashley Sheridan <ash@ashleysheridan.co.uk> wrote: From: Ashley Sheridan <ash@ashleysheridan.co.uk> Subject: Re: [PHP] Login Script: mysql_num_rows(): supplied argument is not a valid MySQL result resource To: "David Hutto" <dwightdhutto@yahoo.com> Cc: php-general@lists.php.net Date: Friday, February 19, 2010, 5:34 AM On Fri, 2010-02-19 at 00:30 -0800, David Hutto wrote: The following script is supposed to validate a username and password in a mysql db.  When entering the username and password of a preregistered user, I get the following errors: Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /var/www/login.php on line 24 Warning: Cannot modify header information - headers already sent by (output started at /var/www/login.php:24) in /var/www/login.php on line 26 On line 24 is: >>>if(!mysql_num_rows($login)) //if the username and pass are wrong --The supplied argument is $login, which is previously defined as: >>>$login = mysql_query("SELECT * FROM 'userinfo' WHERE >>>user = '$user' AND pass = >>>'$pass`"); --which is further defined above it as these values:   $user = $_POST['user']; //pulls the username from the form   $pw = $_POST['pass']; //pulls the pass from the form   $pass = md5($pw); //makes our password an md So why is the sum of those previous definitions an invalid argument for the mysql_query() to test for whether the username and md5 password values are true/equivalent to each other? Thanks for any help you may be able to provide, below is the full login.php page. David ******************************************************** This is the full login.php script, I'm pretty sure no other portions are needed to show at this point for the current problem: <?php $act = $_GET['act']; //retrives the page action if(empty($act)) //if there is no action {   echo('<form action="login.php?act=auth" method="post" name="loginform" id="loginform">   <p>Username   <input type="text" name="user">   </p>   <p>Password   <input type="password" name="pass">   </p>   <p>   <input type="submit" name="Submit" value="Login">   </p>   </form>'); } elseif($act == "auth") //if our page action = auth {   $user = $_POST['user']; //pulls the username from the form   $pw = $_POST['pass']; //pulls the pass from the form   $pass = md5($pw); //makes our password an md5   include("connect.php"); //connects to our mysql database   $login = mysql_query("SELECT * FROM userinfo WHERE user = '$user' AND pass = '$pass`"); //selects info from our table if the row has the same user and pass that our form does   if(!mysql_num_rows($login)) //if the username and pass are wrong   {         header("Location: login.php");  //redirects to our login page         die(); //stops the page from going any further   }   else   {         setcookie("user", $user, time()+3600);//sets our user cookie                 setcookie("pass", $pass, time()+3600);//sets our pass cookie                 header("Location: memprar.php");//instead of yourpage.php it would be your protected page   } } ?> First, please create a new email when sending to the list and don't just reply to the last one, as those of us with email clients that group by threads get confused when the subject line appears to change mid-thread! On to your question, you've got an error with your query, so it will never work: "SELECT * FROM userinfo WHERE user = '$user' AND pass = '$pass`"    // change that last back tick after $pass! Lastly; protect your queries! That $user variable is open to injection. Replacing it with something like $user = mysql_real_escape_string($_POST['user']); Your $pass is protected (I believe) because of what you're doing with the hash, but I'm not an expert in these things, so it could be that this may not be enough. Thanks, Ash http://www.ashleysheridan.co.uk Apologies for hijacking the thread, I hit reply all in a randomly picked email and deleted the info/subject line, guess that doesn't work. Thanks for the advice, it's almost working right, all things considered. David