<?php

$database_name='';
$database_username='';
$database_password='';

$connection = mysqli_connect('localhost',$database_username,$database_password);

if(!$connection) {
    echo "Cannot connect to the database – incorrect details";
} else{
    mysqli_select_db($connection, $database_name);
    $result=mysqli_query($connection, 'show tables');

    while($tables = mysqli_fetch_array($result)) {

        foreach ($tables as $key => $value) {
        	//echo "ALTER TABLE ".$value." CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci<br>";
            mysqli_query( $connection, "ALTER TABLE ".$value." CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci");
        }
    }
echo "Successfull collation change!";
}

mysqli_close($connection);