[Sheryld]

метод для обмена двух узлов:

function SwapNodes($categoryID1, $categoryID2)
		{
			if ($this->getNodeInfo($categoryID1) == 0)
			{
				$nodeInfo1 = $this->nodeInfo;
			}
			if ($this->getNodeInfo($categoryID2) == 0)
			{
				$nodeInfo2 = $this->nodeInfo;
			}
			// todo:
			// check for rule: both nodes must have same parentID
			$db = new MySql(null, "mport4", null, null);
			$db->MySql_Connect();
			$db->MySql_SelectDb();
			
			$updateQuery = "update categories set
			cat_LEFT = case 
			when cat_LEFT between " . $nodeInfo1["left"] . " and " . $nodeInfo1["right"] . " then " . 
			$nodeInfo2["right"] . "+cat_LEFT-" . $nodeInfo1["right"] .
			" when cat_LEFT between " . $nodeInfo2["left"] . " and " . $nodeInfo2["right"] . " then "  .
			$nodeInfo1["left"] . "+cat_LEFT-" . $nodeInfo2["left"] . " else " .
			$nodeInfo1["left"] . "+" .  $nodeInfo2["right"] . "+cat_LEFT-" . $nodeInfo1["right"] . "-" . $nodeInfo2["left"] . " end," .
			" cat_RIGHT = case
			when cat_RIGHT between " . $nodeInfo1["left"] . " and " .  $nodeInfo1["right"] . " then " .
			$nodeInfo2["right"]  . "+cat_RIGHT-" . $nodeInfo1["right"] .
			" when cat_RIGHT between " . $nodeInfo2["left"] . " and " . $nodeInfo2["right"] . " then " .
			$nodeInfo1["left"] . "+cat_RIGHT-" . $nodeInfo2["left"] . " else " .
			$nodeInfo1["left"] . "+" . $nodeInfo2["right"] . "+cat_RIGHT-" . $nodeInfo1["right"] . "-" . $nodeInfo2["left"] . " end " .
			" where cat_LEFT between " . $nodeInfo1["left"] . " and " . $nodeInfo2["right"] . 
			" and " . $nodeInfo1["left"] . "<" . $nodeInfo1["right"] . 
			" and " . $nodeInfo1["right"] . "<" . $nodeInfo2["left"] .
			" and " . $nodeInfo2["left"] . "<" . $nodeInfo2["right"];
			
			$db->MySql_QueryDb($updateQuery);
			
			if (mysql_affected_rows($db->dbConn) > 0)
			{
				return 0;				
			}
			return -1;			
		}

p.s. нужно добавить проверки.