m8.php

<?php
//MySQL Update data
$host     = 'localhost';
$user     = 'root';
$password = 'root';

$db_name = 'basicDB_2';
//students_2

$mysql_conn = mysqli_connect( $host, $user, $password, $db_name );

if ( !$mysql_conn ) {
    die( "Connection Failed" . mysqli_connect_error() );
}

$sql = "UPDATE students_2 SET firstname='Kamaal', lastname='Hossain', email='kamal@kamal.com' WHERE id=12";

if ( mysqli_query( $mysql_conn, $sql ) ) {
    echo "Record Updated Successfully";
} else {
    echo "Error updating failed" . mysqli_error( $mysql_conn );
}

mysqli_close( $mysql_conn );