#(\d{2})\.(\d{2})#s 11.11
#(\d{2})\.(\d){4})#s 11.1111
#(\d{2})\.(\d{2})\.(\d{4})#s 11.11.1111

preg_match("#(\d){2}\.{\d}{2}#s", "$search");

<?php
$search = 'Поисковый запрос с датой 33.12'; 
preg_match_all("#(\d{2})\.(\d{2})#s", $search, $matches);
print_r($matches);


Array
(
    [0] => Array
        (
            [0] => 33.12
        )

    [1] => Array
        (
            [0] => 33
        )

    [2] => Array
        (
            [0] => 12
        )

)

<?php
$search = 'Поисковый запрос с датой 33.12'; 
preg_match_all("#(\d{2})\.(\d{2})#s", $search, $matches, PREG_SET_ORDER);
print_r($matches);

/*

Array
(
    [0] => Array
        (
            [0] => 33.12
            [1] => 33
            [2] => 12
        )

)
*/

if (!empty($search)) 
{	$search=parseString($search);
	if (preg_match("/^\d{2}\.\d{4}$/", $search))
	{	$parts=explode(".",$search);
		$search=$parts[1]."-".$parts[0];
	}
	if (preg_match("/^\d{2}\.\d{2}$/", $search))
	{	$parts=explode(".",$search);
		$search=$parts[1]."-".$parts[0];
	}
	if (preg_match("/^\d{2}\.\d{2}\.\d{4}$/", $search))
	{	$parts=explode(".",$search);
		$search=$parts[2]."-".$parts[1]."-".$parts[0];
	}
}
$query="SELECT * FROM `$tab` WHERE `nazva` LIKE '%".$search."%' OR `nomer` LIKE '%".$search."%' OR `srok` LIKE '%".$search."%' OR `kontrol_srok` LIKE '%".$search."%' OR `rezoluciya` LIKE '%".$search."%' ORDER BY `$ORDERBY` $ASCDESC";