Is Child Node? - With HierarchyId Data Type in SQL Server 2008 by serverku

Various method I have introduced in my earlier posts, like How to get levels of hierarchy nodes, get up-line and down-line of nodes, get string paths of nodes and get next available nodes.

I hope you have read all of them and you liked too. In this post I am presenting how can we know the node is child of particular node or not? Before going ahead to run the script and see the output of hierarchy structure.

-- Create database and table
CREATE DATABASE HierarchyDB

GO

USE HierarchyDB

GO

IF ( Object_id('HierarchyTab') > 0 )
DROP TABLE HierarchyTab

GO

CREATE TABLE HierarchyTab
(
NodeId     INT IDENTITY(1, 1)
,NodeDepth VARCHAR(100) NOT NULL
,NodePath  HIERARCHYID NOT NULL
,NodeDesc  VARCHAR(100)
)

GO 

-- Creating constraint on hierarchy data type.
ALTER TABLE HierarchyTab ADD CONSTRAINT U_NodePath UNIQUE CLUSTERED (NodePath)

GO 
-- Inserting data in above creatd table.
INSERT INTO HierarchyTab(NodeDepth,NodePath,NodeDesc)
VALUES 
('1',HIERARCHYID::Parse('/'),'Node-1'),
('1.1',HIERARCHYID::Parse('/1/'),'Node-2'),
('1.1.1',HIERARCHYID::Parse('/1/1/'),'Node-3'),
('1.1.2',HIERARCHYID::Parse('/1/2/'),'Node-4'),
('1.2',HIERARCHYID::Parse('/2/'),'Node-5'),
('1.2.1',HIERARCHYID::Parse('/2/1/'),'Node-6'),
('1.2.2',HIERARCHYID::Parse('/2/2/'),'Node-7'),
('1.2.2.1',HIERARCHYID::Parse('/2/2/1/'),'Node-8'),
('1.2.2.1.1',HIERARCHYID::Parse('/2/2/1/1/'),'Node-9'),
('1.2.2.1.2',HIERARCHYID::Parse('/2/2/1/2/'),'Node-10'),
('1.3',HIERARCHYID::Parse('/3/'),'Node-11'),
('1.3.1',HIERARCHYID::Parse('/3/1/'),'Node-12'),
('1.3.2',HIERARCHYID::Parse('/3/2/'),'Node-13'),
('1.4',HIERARCHYID::Parse('/4/'),'Node-14')

GO

Here is the logical image of the above data are as follows,

(Click on image to enlarge)

So our topic here, Is the node Child ?

IsDescendantOf() : This functions will return 1 if the node is child of given node, return 0 if the node is not child.

Let's run the script with example as who are child of hierarchy node "1".

SELECT 
NodePath.GetLevel() AS NodeLevel,
NodePath.ToString() AS NodeStringPath,
NodePath.GetAncestor(1).ToString() AS ParentNode,
NodePath.IsDescendantOf(HIERARCHYID::Parse('/1/')) IsParent,
-- Above line will return 1 or 0
NodeId,
NodeDepth,
NodePath,
NodeDesc
FROM HierarchyTab

GO

You can see the above image and check parent node for appropriate child nodes. Hope you like this. Stay tuned for more.