Chyba v sql příkazu

 $sql = "UPDATE `tabulka` SET `firstname` = ".$db->sql_string($ar[18]).", 
												`surname` = ".$db->sql_string($ar[19]).", 
												`hoteltaxi = ".$db->sql_integer($ar[1]).", 
												`pax` = ".$db->sql_integer($ar[2]).", 
												`starttime` = '".trim(date("Y-m-d H:i:s", mktime(givFromZeroNULL($ar[7]), givFromZeroNULL($ar[8]), 0, givFromZeroNULL($ar[5]), givFromZeroNULL($ar[4]), givFromYearNULL($ar[6]))))."', ";
												if($ar[10] && $ar[11] && $ar[12] && $ar[13] && $ar[14]) {
												$sql .= "`pickuptime` = '".date("Y-m-d H:i:s", mktime(givFromZeroNULL($ar[13]), givFromZeroNULL($ar[14]), 0, givFromZeroNULL($ar[11]), givFromZeroNULL($ar[10]), givFromYearNULL($ar[12])))."', ";
												}
												
												$sql .= " 
												`hotelname` =  ".$db->sql_string($ar[9]).", 
												`price` =  ".$db->sql_double($ar[15]).", 
												`currency` =  ".$db->sql_string($ar[16]).", 
												`payment` =  ".$db->sql_string($ar[17]).", 
												`preselection` =  ".$db->sql_string($ar[20]).", 
												`phone` =  ".$db->sql_integer($ar[21]).", 
												`email` =  ".$db->sql_string($ar[22]).", 
												`note` =  ".$db->sql_string($ar[23]).", 
												`next_note` =  ".$db->sql_string($ar[24]).", 
												`is_ended` =  ".$db->sql_integer(1).", 
												`datein` = NOW()  
												WHERE
												`control_hash` = ".$db->sql_string($ar[25])." and id = ".$db->sql_integer($_SESSION['control_id'])." 
												";
												
												
									///////////////////////////////
									////// Zkusíme uložit /////
									///////////////////////////////
										
										$c = $db->execute($sql, __FILE__, __LINE__);

 // escape znaků ' " '
  function sql_string($txt) {

  $txt = trim($txt);
		$txt = eregi_replace("select", " ", $txt);
		$txt = eregi_replace("drop", " ", $txt);
		$txt = eregi_replace(";", " ", $txt);
		$txt = eregi_replace("--", " ", $txt);
		$txt = eregi_replace("insert", " ", $txt);
		$txt = eregi_replace("delete", " ", $txt);
		$txt = eregi_replace("xp_", " ", $txt);
		$txt = trim($this->mysqli->real_escape_string($txt));
      return "'". $txt ."'";  
	
   }
	  
	function sql_integer($int) {
      return intval(trim($int) + 0);  
	}
	
	function sql_double($int) {
      return round(trim($int), 1);  
	}