Smarty

You could read the manual on section loops, to start with:
http://smarty.php.net/manual/en/language.function.section.php

{if is_numeric($smartyVar)}

Any PHP function would work.

Do these not help?
http://www.phpinsider.com/smarty-forum/viewtopic.php?p=38428#38428
http://www.phpinsider.com/smarty-forum/viewtopic.php?p=38485#38485

The tags put you into PHP. You do whatever you want with it that you want to, using normal PHP code.

So you only want to list the days that have events in them? All of this code is untested.

$first_day = date('Y-n-d', mktime() + (3600 * $tz));
$last_day = date('Y-n- ...

I bet the problem you were having was with the query itself...

$sql = 'SELECT categories.id AS cat_id, sub_categories.id AS sub_id, category_name, sub_name FROM categories INNER JOIN sub_categories ...

You shouldn't, and you can't, unless you escape into {php}{/php} tags.

All code untested, so please mind any typos.

$sql = 'SELECT * FROM categories INNER JOIN sub_categories ON (categories.id = sub_categories.cat_id)';

$result = mysql_query($sql); ...

About your first post:

http://smarty.php.net/manual/en/variable.error.reporting.php

You can also pre-register anything you want:
http://smarty.php.net/manual/en/api.register.function.php

...

could you verify that the pages are being written to your /cache/ directory for us?

Is $totalPagini an array, like the "from=" value is expecting?

If it's just an integer value, then I think you need to stick with the section loop.

Probably this (untested):

{section loop=$totalPagini name='page'}
{if $page == $smarty.section.page.iteration}
<strong> {$smarty.section.page.iteration} &l ...

I suggest you use this:
http://php.net/manual/en/ref.apc.php

It will keep your most commonly requested PHP files cached in memory in bytecode format. Compiling to bytecode automatically removes c ...

I don't think {html_table} supports multi-dimensional arrays.

This is indeed the wrong forum to ask.

but...

echo date('c', strtotime('-1 day', strtotime('2006-12-21 17:54:09')));

You'll need to lookup the date function in php and change 'c' to the exact ...