Need some help with an error

code_junkie · 10-13-2009, 02:59 PM

Ok so I've been trying to teach myself php and am doing pretty good so far. I am making a little newsletter sign up for a site and it works fine, but I get an error. From what I understand this error should not allow the script to continue if it happens, but it doesn't and the script runs. The error is:

Code:

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

And like I said the script runs fine, might not be the best way to do it, its a start. Here is what I have done.

Code:

if(isset($_POST['submit'])) {
		//Set variables.
		$firstname = strip_tags($_POST['firstname']);
		$lastname = strip_tags($_POST['lastname']);
		$email = $_POST['emailaddress'];
		$accept = $_POST['accept'];
		
		// Check for empty fields.
		if (empty($firstname) || empty($lastname) || empty($emailaddress)) {
			$message = "Please fill in all fields!";
		} else {
			$message = "All fields have been filled in!";
			// If successful, continue sign up proccess.
			// Check to see if info already exist.
			$sql = "SELECT * FROM mailing_list WHERE firstname = '$firstname' AND lastname = '$lastname' AND email = '$emailaddress'";
			$result = mysql_query($sql) or die(mysql_error());
			if(mysql_num_rows($result) != 0) {
				$message = "This information already exist!";
			} else {
				// If information doesn't exist, add it.
				$sql = "INSERT INTO mailing_list (id, firstname, lastname, email, accept) VALUES (null, '$firstname', '$lastname', '$emailaddress', '$accept')";
				$result = mysql_query($sql) or die(mysql_error());
				if(mysql_num_rows($result) != 0) {
					$message = "Users information was not added!";
				} else {
					$message = "Users information was added successfully!";
				}
			}
		}
	} else {
	}

How can I fix what is triggering this error or stop it from showing?

adamdecaf · 10-14-2009, 12:08 AM

Correct me if I'm wrong but not all browses seem to send a undefined value for blank form fields, some tend to send '' (aka, nothing [blank string]).

PHP Code:


			
function is_empty($value){
    if ($value === '' || empty($value)){
         return false;
    }
return true;
}

if (is_empty($firstname) || is_empty($lastname) || is_empty($emailaddress)) {
            $message = "Please fill in all fields!";
        } else {

Alan @ CIT · 10-24-2009, 07:38 PM

You're using mysql_num_rows() in 2 places and I'm guessing that it is the second one (after the INSERT) that is causing the error?

mysql_num_rows() only works on SELECT statements, for your INSERT statement, try using mysql_affected_rows() instead - that should return 1 if the new info was inserted into the database, or -1 if there was a problem.

More info: http://uk.php.net/manual/en/function...ected-rows.php