Index on HierarchyID : Handling Hierarchical data inside the database Part1

Index on HierarchyID : Handling Hierarchical data inside the database Part1

Sometimes we need to handle hierarchical data in databases like trees where data elements are having relationship like parent and child. Before SQL Server 2008 it was complicated to deal with such kind of data. Inside SQL Server 2008 Microsoft introduces a new data type  Index on HierarchyID to handle such type of data and reduce the complexity. By using this data type you can also use various methods provided by SQL Server to deal with such data. Here we will see how can, we use it:

USE Master
go
create database HierarchyTest
go
USE HierarchyTest
go
create table xtHid
(
    id HierarchyID,
    name varchar(20)
)

Now insert first data row with below code:

insert into xtHid values(HierarchyID::GetRoot(),'Microsoft')
go

Now if you want to see the data inside that table then

Select * from xtHid
go

Let’s insert some more data:

declare @count int
declare @search varchar(20)
declare @insert varchar(20)
declare @temp1 hierarchyID
declare @temp2 hierarchyID
set @count=0
while @count<6
begin
if (@count=0)
begin
    set @search='Microsoft'
    set @insert='SQLServer'
end
if (@count=1)
begin
    set @search='SQLServer'
    set @insert='SQLServer2005'
end
if (@count=2)
begin
    set @search='SQLServer'
    set @insert='SQLServer2008'
end
if (@count=3)
begin
    set @search='SQLServer'
    set @insert='SQLServer2012'
end
if (@count=4)
begin
    set @search='Microsoft'
    set @insert='MSOffice'
end
if (@count=5)
begin
    set @search='MSOffice'
    set @insert='MSOffice2010'
end
    Select @temp1=id from xtHid where name=@search
    Select @temp2=max(id) from xtHid where id.GetAncestor(1)=@temp1
    Insert into xtHid values(@temp1.GetDescendant(@temp2,NULL),@insert)
    Set @count=@count+1
end

Now just Select the data from above table:

Select * from xtHid

Here the output of id column is not clear, so we can use ToString() method on id column here to make the output as more readable and understandable:

Select id.ToString() as id, name from xthid

Here the above output is clearer.

Regards

Prince Rastogi

Like us on FaceBook  |  Follow us on Twitter | Join the fastest growing SQL Server group on FaceBook

Follow me on Twitter |  Follow me on FaceBook