$link = mysql_connect('<servidor>', '<usuario>', '<password>');
if (!$link)
{
	die('Could not connect: ' . mysql_error());
}
mysql_select_db('-basededatos-', $link) or die('Could not select database: ' . mysql_error() );

$tables = mysql_query( 'SHOW TABLES' );
if (!$tables)
{
	echo 'Could not run query: ' . mysql_error();
	exit;
}
if (mysql_num_rows($tables) <= 0)
{
	die;
}

while ($table = mysql_fetch_array( $tables ) )
{
	$columns = mysql_query( 'SHOW COLUMNS FROM `' . $table[ 0 ] . '` where Extra = "auto_increment"' );
	if (!$columns)
	{
		echo 'Could not run query: ' . mysql_error();
		die;
	}
	if (mysql_num_rows( $columns ) > 0) 
	{
		while ( $col = mysql_fetch_assoc( $columns ) ) 
		{
			echo sprintf( "ALTER TABLE `%s` CHANGE `%s` `%s` %s auto_increment;\n",
				$table[ 0 ],
				$col[ 'Field' ],
				$col[ 'Field' ],
				$col[ 'Type' ]
			);
		}
	}
}
mysql_close($link);