mysql_num_rows problem

aaron118

I am trying to create a login script and I use the following code to query the database:

	$query = "SELECT * FROM customers WHERE username='$username' AND userpass= '$password'";
	$result = mysql_query($query);
        $rows = mysql_num_rows($result);

But I always get the error: Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource

It's only the

$rows = mysql_num_rows($result);

line that casuses the error, what is wrong with that line?

Thanks

drew010

the query probably failed.
put

if (!$result) {
  echo mysql_error();
  exit;
}

just after mysql_query(). see what it says and correct the problem.

TimTimTimma

Originally posted by aaron118
I am trying to create a login script and I use the following code to query the database:
	$query = "SELECT * FROM customers WHERE username='$username' AND userpass= '$password'";
	$result = mysql_query($query);
        $rows = mysql_num_rows($result);
But I always get the error: Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource

It's only the
$rows = mysql_num_rows($result);
line that casuses the error, what is wrong with that line?

Thanks [/B]

more then likely you misspelled one of the fields, or mistyped something in the query part, thats a common problem I run into.

Napster

Yes deffinatly, the problem is in the MySQL Query. That is a common misconception people who are new to PHP have. Although the PHP is having a problem with an error on that line, that does not neccessarily mean that you can fix it on that line.

aaron118

I don't think it can be the query as I have checked it. I am trying to create a login script and the user enters their username and password on a html form which gets posted to a php page which checks if the username and password exists in the DB. Here is the PHP code again to check that:

	$query = "SELECT * FROM customers WHERE username='".$_REQUEST['username']."' AND userpass='".$_REQUEST['password']."' LIMIT 1";
	$result = mysql_query($query);
	$num_rows = mysql_num_rows($result);

I can't see a problem there and all fields are spelt correctly. Why is it still giving me that error?

Thanks

drew010

again, try

echo mysql_error();

after mysql_query and see if there is a problem

bradgrafelman

Also, you might want to take a peek at the Debugging 101 thread.