<?php
$hostname = 'localhost';
$username = 'YOUR-DB-USERNAME';
$password = 'YOUR-DB-PASSWORD';
$database = 'YOUR-DB-NAME';
$collation = 'utf8mb4_unicode_ci';

$db = new mysqli( $hostname, $username, $password, $database );

if( $db->connect_errno ) {
	echo "ERROR: Cannot connect to the database - " . $db->connect_error;
}
else {
	$query = 'show tables';
	$result = $db->query( $query );

	echo '<p>Altering all tables in ' . $database . ' to ' . $collation .'</p>';

	while( $row = $result->fetch_array( MYSQLI_NUM ) ) {
		$alterresult = $db->query( 'ALTER TABLE ' . $row[0] . ' COLLATE ' . $collation );
		if( !$alterresult ) {
	 		echo $row[0] . ' - ERROR: NOT ALTERED</br>';
		}
		else {
	 		echo $row[0] . ' - Altered</br>';
		}
	}

	echo '<p>The collation of your database tables has been successfully changed!</p>';
}