What is meant by "supplied argument is not a valid MySQL result"?

[JerryGolem]

I am new to mysql and have created a script that is trying to access a database that I have created on my ISP. I have no idea what the following message means. Please help. I got the example from "Create Dynamic Web Pages Using PHP and Mysql" by David Tansley.

Message:
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/jgolem/public_html/insertcust.php on line 48

Code:
$sql = 'SELECT `CustomerEmail` FROM `CustomerInformation` WHERE 1 AND `CustomerEmail` = \'jgolem@hotmail.com\' LIMIT 0, 30';
# Line 41

$result=mysql_query($sql,$connection);
$num_rows=mysql_num_rows($result);

 

[danielhozac]

That means that you don't check for errors. A simple [tt]or die("Error: " . mysql_error())[/tt] after [tt]mysql_query($sql)[/tt] would help you diagnose the problem. //Daniel

 

[JerryGolem]

Thank you Daniel!!! This got me through a tough time.