Sql [hierarchyid]类型如何动态插入层级数据

[hierarchyid] 是个不错的数据类型，能够方便的操作树型结构，网上找了很多资料没找到如何做到动态插入节点的例子，只好从MSDN认真看了下资料写出了一个DEMO

CREATE TABLE  EmployeeOrg
(
   OrgNode hierarchyid PRIMARY KEY CLUSTERED,
   OrgLevel AS OrgNode.GetLevel(),
   EmployeeID int UNIQUE NOT NULL,
   EmpName varchar(20) NOT NULL,
   Title varchar(20) NULL
) ;
go

CREATE PROC AddEmp(@mgrid int, @empid int, @e_name varchar(20), @title varchar(20))
AS
BEGIN
   DECLARE @mOrgNode hierarchyid, @lc hierarchyid
   SELECT @mOrgNode = OrgNode
   FROM  EmployeeOrg
   WHERE EmployeeID = @mgrid
   SET TRANSACTION ISOLATION LEVEL SERIALIZABLE
   BEGIN TRANSACTION
      SELECT @lc = max(OrgNode)
      FROM  EmployeeOrg
      WHERE OrgNode.GetAncestor(1) =@mOrgNode ;

      INSERT  EmployeeOrg (OrgNode, EmployeeID, EmpName, Title)
      VALUES(@mOrgNode.GetDescendant(@lc, NULL), @empid, @e_name, @title)
   COMMIT
END ;

go

--插入根
INSERT  EmployeeOrg (OrgNode, EmployeeID, EmpName, Title)
VALUES (hierarchyid::GetRoot(), 1, '蓝灯', 'Marketing Manager')
go
--随机数
declare @p1 int
select @p1=convert(int, 100000000*rand())
declare @p2 int
select @p2=convert(int, 100000000*rand())

--插入软件部门子集
EXEC AddEmp 1, @p1, '研发部门老大', 'Marketing Specialist' ;
EXEC AddEmp 1, @p2, '测试部门老大', 'Marketing Specialist' ;

go

select * from EmployeeOrg