<?php

$db = mysql_connect('localhost','username','password');

if(!$db) echo "Kann nicht zur Datenbank verbinden!".chr(10);

mysql_select_db('database');

$result=mysql_query('show tables');

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

 foreach ($tables as $key => $value) {

   $query = "ALTER TABLE $value CONVERT TO CHARACTER SET utf8 ↩

             COLLATE utf8_unicode_ci"; 

   echo $query.chr(10);

   mysql_query($query);

   if (mysql_error()) echo mysql_error().chr(10);

 }

}

echo "Erledigt!".chr(10);

?>