Re: Beginners issue with mysql_num_rows()

From: Pedro Graca (hexkid_at_hotpop.com)
Date: 02/26/04

  • Next message: Ken: "PHP reading of JAvascript" 
    Date: 26 Feb 2004 20:24:53 GMT

    David Nikel wrote:
    > The following snippet of code:
    >
    > $query = "select * from auth where username='$username' and
    > password=password('$password')";
    > $result = mysql_query($query, $db_conn);
    > $num = mysql_num_rows($result);
    > echo $num;
    >
    > produces the following result:
    >
    > Warning: mysql_num_rows(): supplied argument is not a valid MySQL
    > result resource in prototype4\admin.php on line 14

    This means the mysql_query() call produced /something/ that is not valid
    for mysql_num_rows() (probably your call has the same effect as
      $result = false;
    and you can't do mysql_num_rows(false);).

    > I've searched high and low and cannot find a reason why this isn't
    > working.

    I can't tell what's wrong either -- but why not let PHP/MySQL tell you?

    $result = mysql_query($query, $db_conn) or die(mysql_error() . ' on ' . $query);

    > I am however, a beginner to PHP, so please forgive me if
    > there's an obvious mistake!

    Maybe $username and $password are not what you think they are?

    Are these variables 'sanitized'? You don't want to pass "Mc'Donald" to
    the query "as is".

    Except for the lack of error-checking (and possibly making the variables
    safe) I see nothing wrong.

    > Thanks in advance for any help anyone can give

    You're welcome. Hope this helps. 

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