<?php
include 'dbconnect.php';
$home_id=$_POST['product'];
$limit = "SELECT * FROM product WHERE top='1'";
$mysqliStatus = $conn->query($limit);
if(mysqli_num_rows($mysqliStatus) >= 15) {
    echo "<script> alert('Limit Exceed'); window.location.href='top_offer_list.php'; </script>";
} else {
$sql = "UPDATE product SET top='1' WHERE id=$home_id"; 
if ($conn->query($sql) === TRUE)
         {
              echo "<script> alert('Successfull'); window.location.href='top_offer_list.php'; </script>";

        } 
      else 
         {
           echo "Error: " . $sql . "<br>" . $conn->error;
         }
}
?>