Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource

<?php
// Include the database connection file.
include("connection.php");

// username and password sent from form
$username=$_POST['myusername'];
$password=$_POST['mypassword'];

// To protect MySQL injection (more detail about MySQL injection)
$username = stripslashes($username);
$password = stripslashes($password);
$username = mysql_real_escape_string($username);
$password = mysql_real_escape_string($password);

$sql=$query = "select * from users where f_name = ".$username ." AND p_wrd = ".$password." ";
$result=mysql_query($sql);

//Count results
$rowNo = mysql_num_rows($result);
if ($rowNo =1){
// Register $myusername, $mypassword
session_register("myusername");
session_register("mypassword");
}
else {
echo "Wrong Username or Password";
}
?>

This was working before, I am not sure why it is not working anymore?

 

heres your problem:

should be

you were asigning it the value 1 , rather than equating it to.

Graham

 

Also, I'd recommend to add a @ sign in front of mysql_num_rows to avoid errors in case the table is empty or returned zero results:

$rowNo = @mysql_num_rows($result);

PHP:

 

also you may want to trim the white space from the passwords:

Just a tip.

also this is wrong:

just:

would dso the jobby

Graham

 

also echo/print or sql statement this help a lot

 

Replace

$result=mysql_query($sql);

Code (markup):

With

$result=mysql_query($sql);
if($result === false)
{
   die(mysql_error());
}

Code (markup):

Then try it and it should display an error
What is that error ?

 

Why not just

$result = mysql_query($sql) or die(mysql_error());

PHP: