please resolve the erroe

Question

<?php
//Grab User submitted information
$firstname = &_POST["firstname"];
$lastname = &_POST["lastname"];
//connect to the database
$con = mysqli_connect("localhost","root","","test");
//Make sure we connected successfully
if(! $con)
{
die('connection Failed'.mysqli_error());
}
//select the database to use
mysqli_select_bd($con,"test");
$result = mysqli_query($con,"SELECT firstname, lastname FROM try WHERE firstname =$firstname and lastname = $lastname");
$row = mysqli_fetch_array($result);
if($row["firstname"]==$firstname && $row["lastname"]==$lastname)
echo"You are a validated user.";
else
echo"sorry, your credentials are not valid, Please try again.";
?>
& the error is->Fatal error: Cannot use temporary expression in write context in C:\xampp\htdocs\kosis.php on line 3

Answer 1

// replace &_POST -> $_POST
$firstname = $_POST["firstname"];
$lastname = $_POST["lastname"];
//select the database to use
//mysqli_select_bd -> mysqli_select_db
mysqli_select_db($con,"test");
// add single quotes around
// field values
$result = mysqli_query($con,"SELECT firstname, lastname FROM try WHERE firstname ='$firstname' and lastname = '$lastname'");