CIBlockProperty::_Update

function _Update($ID, $arFields, $bCheckDescription = false)
{
	global $DB;
	$ID=intval($ID);
	$rsProperty = $this->GetByID($ID);
	$arProperty = $rsProperty->Fetch();
	if(!$arProperty)
	{
		$this->LAST_ERROR = $this->FormatNotFoundError($ID);
		return false;
	}
	BitrixIblockPropertyIndexManager::onPropertyUpdate($arProperty["IBLOCK_ID"], $arProperty, $arFields);
	if($arProperty["VERSION"]!=2)
	{
		return true;
	}
	$tableFields = $DB->GetTableFields("b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]);
	if(is_set($arFields, "MULTIPLE") && $arFields["MULTIPLE"]!=$arProperty["MULTIPLE"])
	{//MULTIPLE changed
		if($arFields["MULTIPLE"]=="Y")
		{//MULTIPLE=Y
			$strSql = "
				INSERT INTO b_iblock_element_prop_m".$arProperty["IBLOCK_ID"]."
				(IBLOCK_ELEMENT_ID, IBLOCK_PROPERTY_ID, VALUE, VALUE_ENUM, VALUE_NUM
				".(isset($tableFields["DESCRIPTION_".$arProperty["ID"]])? ", DESCRIPTION": "")."
				)
				SELECT
					IBLOCK_ELEMENT_ID
					,".$arProperty["ID"]."
					,PROPERTY_".$arProperty["ID"]."
					,".($arProperty["PROPERTY_TYPE"]=="S" || $arProperty["PROPERTY_TYPE"]=="s"?
						"0":
						"PROPERTY_".$arProperty["ID"])."
					,".($arProperty["PROPERTY_TYPE"]=="S" || $arProperty["PROPERTY_TYPE"]=="s"?
						"0":
						"PROPERTY_".$arProperty["ID"])."
					".(isset($tableFields["DESCRIPTION_".$arProperty["ID"]])? ",DESCRIPTION_".$arProperty["ID"]: "")."
				FROM
					b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]."
				WHERE
					PROPERTY_".$arProperty["ID"]." is not null
			";
			if(!$DB->Query($strSql))
			{
				$this->LAST_ERROR = $this->FormatUpdateError($ID, "MY01");
				return false;
			}
			$strSql = "
				UPDATE b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]."
				SET PROPERTY_".$arProperty["ID"]."=null
				".(isset($tableFields["DESCRIPTION_".$arProperty["ID"]])? ", DESCRIPTION_".$arProperty["ID"]."=null": "")."
			";
			if(!$DB->Query($strSql))
			{
				$this->LAST_ERROR =  $this->FormatUpdateError($ID, "MY02");
				return false;
			}
			$strSql = "
				ALTER TABLE b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]."
				CHANGE PROPERTY_".$arProperty["ID"]." PROPERTY_".$arProperty["ID"]." longtext
			";
			if(!$DB->DDL($strSql))
			{
				$this->LAST_ERROR =  $this->FormatUpdateError($ID, "MY03");
				return false;
			}
		}
		else
		{//MULTIPLE=N
			switch($arFields["PROPERTY_TYPE"])
			{
				case "S":
					$strType = "text";
					break;
				case "N":
					$strType = "numeric(18,4)";
					break;
				case "L":
				case "F":
				case "G":
				case "E":
					$strType = "int(11)";
					break;
				default://s - small string
					$strType = "varchar(255)";
			}
			$strSql = "
				ALTER TABLE b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]."
				CHANGE PROPERTY_".$arProperty["ID"]." PROPERTY_".$arProperty["ID"]." ".$strType."
			";
			if(!$DB->DDL($strSql))
			{
				$this->LAST_ERROR =  $this->FormatUpdateError($ID, "MY04");
				return false;
			}
			switch($arFields["PROPERTY_TYPE"])
			{
				case "N":
				case "F":
				case "G":
				case "E":
					$strTrans = "VALUE_NUM";
					break;
				case "L":
					$strTrans = "VALUE_ENUM";
					break;
				case "s":
					$strTrans = "SUBSTRING(VALUE, 0 ,255)";
					break;
				default:
					$strTrans = "VALUE";
			}
			$strSql = "
				UPDATE
					b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]." EL
					,b_iblock_element_prop_m".$arProperty["IBLOCK_ID"]." EN
				SET
					PROPERTY_".$ID." = ".$strTrans."
					".(isset($tableFields["DESCRIPTION_".$ID])? ",DESCRIPTION_".$ID." = DESCRIPTION": "")."
				WHERE
					EN.IBLOCK_ELEMENT_ID = EL.IBLOCK_ELEMENT_ID
					AND EN.IBLOCK_PROPERTY_ID = ".$ID."
			";
			if(!$DB->Query($strSql))
			{
				$this->LAST_ERROR = $this->FormatUpdateError($ID, "MY05");
				return false;
			}
			$strSql = "
				DELETE FROM
					b_iblock_element_prop_m".$arProperty["IBLOCK_ID"]."
				WHERE
					IBLOCK_PROPERTY_ID = ".$ID."
			";
			if(!$DB->Query($strSql))
			{
				$this->LAST_ERROR = $this->FormatUpdateError($ID, "MY06");
				return false;
			}
		}
	}
	else
	{//MULTIPLE not changed
		if(is_set($arFields ,"PROPERTY_TYPE")
		&& $arFields["PROPERTY_TYPE"]!=$arProperty["PROPERTY_TYPE"]
		&& $arProperty["MULTIPLE"]=="N")
		{
			switch($arFields["PROPERTY_TYPE"])
			{
				case "S":
					$strType = "text";
					break;
				case "N":
					$strType = "numeric(18,4)";
					break;
				case "L":
				case "F":
				case "G":
				case "E":
					$strType = "int(11)";
					break;
				default://s - small string
					$strType = "varchar(255)";
			}
			$strSql = "
				ALTER TABLE b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]."
				CHANGE PROPERTY_".$arProperty["ID"]." PROPERTY_".$arProperty["ID"]." ".$strType."
			";
			if(!$DB->DDL($strSql))
			{
				$this->LAST_ERROR =  $this->FormatUpdateError($ID, "MY07");
				return false;
			}
		}
	}

	if(
		$bCheckDescription
		|| (
			array_key_exists("WITH_DESCRIPTION", $arFields)
			&& $arFields["WITH_DESCRIPTION"] != $arProperty["WITH_DESCRIPTION"]
		)
	)
	{//WITH_DESCRIPTION changed
		if ($arFields["WITH_DESCRIPTION"] == "Y")
		{//WITH_DESCRIPTION=Y
			if (!isset($tableFields["DESCRIPTION_".$ID]))
			{
				$strSql = "
					ALTER TABLE b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]."
					ADD DESCRIPTION_".$ID." varchar(255)
				";
				if (!$DB->DDL($strSql))
				{
					$this->LAST_ERROR = $this->FormatUpdateError($ID, "MY08");
					return false;
				}
			}
		}
		else
		{//WITH_DESCRIPTION=N
			if (isset($tableFields["DESCRIPTION_".$ID]))
			{
				$rs = $DB->Query("
					SELECT COUNT(1) CNT
					FROM b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]."
					WHERE DESCRIPTION_".$ID." IS NOT NULL AND DESCRIPTION_".$ID." <> ''
				");
				$ar = $rs->Fetch();
				if ($ar["CNT"] <= 0)
				{
					$strSql = "
						ALTER TABLE b_iblock_element_prop_s".$arProperty["IBLOCK_ID"]."
						DROP DESCRIPTION_".$ID."
					";
					if (!$DB->DDL($strSql))
					{
						$this->LAST_ERROR = $this->FormatUpdateError($ID, "MY09");
						return false;
					}
				}
			}
		}
	}

	return true;
}