Update or Delete Multiple Rows using PHP

DATABASE CONNECTION SCRIPT

<?php
/**
 * These are the database connection details
 */  
 
define("HOST", 'localhost');     // The host you want to connect to.
define("USER", 'root');    		// The database username. 
define("PASSWORD", '');    		// The database password. 
define("DATABASE", 'demo');    	// The database name.

$mysqli = mysqli_connect(HOST, USER, PASSWORD) or die("Unable to connect to MySQL Server: ". mysqli_connect_error());
mysqli_select_db($mysqli, DATABASE) or die("Unable to connect to Database: ". DATABASE);
?>

UPDATE MULTIPLE ROWS SCRIPT

<?php
include "config.php";
if(isset($_POST["userId"]) && trim($_POST["userId"]) != "") 
{
	$vpb_counted_users = count($_POST["userId"]);
	
	for($i=0; $i<$vpb_counted_users; $i++) 
	{
		ob_start();
		
		mysqli_query($mysqli,"update `updated_users_demo` set `firstname` = '".mysqli_real_escape_string($mysqli,trim(strip_tags($_POST["firstname"][$i])))."', `lastname` = '".mysqli_real_escape_string($mysqli,trim(strip_tags($_POST["lastname"][$i])))."', `username` = '".mysqli_real_escape_string($mysqli,trim(strip_tags($_POST["username"][$i])))."', `password` = '".mysqli_real_escape_string($mysqli,trim(strip_tags($_POST["password"][$i])))."' where `id` = '".mysqli_real_escape_string($mysqli,trim(strip_tags($_POST["userId"][$i])))."'");
		
		ob_end_flush();
	}
}
?>

DELETE MULTIPLE ROWS SCRIPT

<?php
include "config.php";

// THE CODE BELOW DELETES THE ROWS SELECTED BY THE USER AFTER CONFIRMING TO DELETE THEM AND REDIRECTS BACK TO THE index.php
if( isset($_POST["users"]) && !empty($_POST["users"]) ) 
{
	for($i=0; $i<$selected_users_id; $i++) 
	{
		ob_start();
		// Delete selected rows from the database
		mysqli_query($mysqli,"delete from `updated_users_demo` where `id` = '".mysqli_real_escape_string($mysqli,trim(strip_tags($_POST["users"][$i])))."'");
		ob_end_flush();
	}
	header("location: index.php"); // REDIRECTS BACK TO THE index.php
	exit();
}
?>

There is a README.txt file in the downloaded folder that gives you information on how to install the system.