I am trying to fetch data from my DB but I am unable to do so. I sometimes do not get any result or sometimes I get failed without pressing the submit button. Please take a look into this code. I know there is something wrong I'm doing but I am unable to sort it out as I am a newbie and in learning process. Kindly take a look in my html and php. Although there is no error in connection with DB I have checked it thrice Its working fine to establisg connection with db. Here is my php code
<?php
if (isset($_POST['login']))
{
    include "config.php";
    $username=mysqli_real_escape_string ($conn,$_POST['user']);
    $password=$_POST['user'];
    $sql="SELECT username, password FROM user WHERE username='{$username}' AND password='{$password}'";
    $result = mysqli_query($conn,$sql) or die("Query failed");
    if (mysqli_num_rows($result)>0)
    {
       while( $row=mysqli_fetch_assoc($result))
       {
           echo "Successful";
       }
    }
    else
    {
        echo 'failed ';
    }
}
?>
My DB configures successfully, there's no error in config.php.
html is here
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