$servername = "localhost"; //host name
$username = "username"; //username
$password = "password"; //password
$mysql_database = "dbname"; //database name
$conn = mysqli_connect($servername, $username, $password) or die("Connection failed: " . mysqli_connect_error());
mysqli_select_db($conn,$mysql_database) or die("Opps some thing went wrong");
$stmt = $conn->prepare("SELECT * FROM $tbl_name WHERE username=? and password=? ");
$stmt->bind_param('ss',$myusername,$mypassword);
$stmt->execute();
$get_result =$stmt->get_result();
$row_count= $get_result->num_rows;
if($row_count>0)
{
echo "valid user ";
}
else
{
echo "not valid user";
}