num_row errors

Hi, i need help to solve this case, I'm trying to create login forms, and i got errors it said
"mysql_num_rows() expects parameter 1 to be resource, boolean given in line 18.

i can't figure out what this mean and how to solve it. here is code, please see line 18 in bold where it said

$count=mysql_num_rows($result);

Code:

---

ob_start();
// Connect to server and select databse.
include ('conn.php');
// Define $myusername and $mypassword
$myusername=$_POST['username'];
$mypassword=$_POST['password'];
// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);
$sql="SELECT * FROM `members` WHERE username='$myusername' and password='$mypassword'";
//echo  $sql;

$result=mysql_query($sql);
// Mysql_num_row is counting table row
$count=mysql_num_rows($result);

// If result matched $myusername and $mypassword, table row must be 1 row

if($count==1){
// Register $myusername, $mypassword and redirect to file "login_success.php"
echo $myusername;
$_SESSION['myusername'] = $myusername;
//header("location:login_success.php");
}
else {
echo "";
//header("location:index.php?a='failed'");
}
ob_flush();
?>

---

can anyone help me what to write that code to solve this, because I'm still not get it.

thanks.

AM

It means the query failed for some reason and returned a Boolean false instead of a query result resource. Therefore you need to debug your query and also consider adding some defensive coding, so that you only call mysql_num_rows() if the query did not fail (i.e. is not false).

like this!

$sql="SELECT * FROM `members` WHERE username='$myusername' and password='$mypassword'";
if(!$result) die ('Unable to run query:'.mysql_error());

but i'm still getting new errors the result said "unable to run query).

what this mean!

AM

You might try running the query in phpMyadmin to make sure the query returns the right data. Is the conn.php connecting ok?

It is not a good practice to store the password in a readable format. It is best to encrypt the password. That way if your site is hacked the passwords will not be stolen along with usernames. When encrypted you just re-encrypt the login and compare encrypted to encrypted.

So I can assist you please report the errors you are getting with

<?php
error_reporting(E_ALL);
?>

Post them here and help will come.