Hi, currently working on tutorial on how to create simple login php for my juniors.

I learnt to create login php using dreamweaver cs4 and xampp, it works. This time, I try to modify the code and using zymic database http://mysqlquery.zymichost.com

first i create the index.html


<form action="login.php" method="POST">
    Username: <input type="text" name="username"> <p>
    Password :<input type="password" name="password"> <p>
    <input type="submit" name="submit" value="Login">


and then login.php


session_start () ;

$username = $_POST ['username'];
$password = $_POST ['password'];

if ($username&&$password)

        $connect = mysql_connect("localhost", "704286_xxx", "xxxxxx") or die ( "Couldnt connect to database") ;
        mysql_select_db ("xxxx_xxx_logindb") or die ("Couldnt find database ");

        $query = mysql_query ("SELECT * FROM users WHERE username='$username'");    
        $numrows = mysql_num_rows($query);
        if($numrows !=0)


        while ($row = mysql_fetch_assoc($query))
            $dbusername = $row ['username'];
            $dbpassword = $row ['password'];

            if ($username==$dbusername&&$password==$dbpassword)
                echo "Login successful. <a href='member.php'> Click here to enter the members area</a>";
                $_SESSION ['username']=$dbusername;
            echo "Incorrect password";

        die ("That username doesnt exist");
 die ("Please enter a username and password");


I uploaded these files using Filezilla. The index.html does works but when I key in the username & password that I have in my database, it shows : **Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /www/zxq.net/j/c/l/jclinx/htdocs/login.php on line 15
That username doesnt exist **

In my SQLBUDDY, I've added two usernames & passwords: katyperry & xyz9 and ladygaga & abc1.

Somebody please help, what is line 15 about actually? T.T

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It seems that your sql is invalid. Check that the users table exists and that it has a username field. In addition, you fail to clean the input data. You must do this, e.g. with mysql_real_escape_string().