Definately looks like a job for a recursive CTE in order to build the Path then a simple update after, this is a simple test rig for a select, but the update isnt too bad.

drop table #hirNode

go

Create Table #hirNode(

hirNode Int

,hirNodeParent int

,Title varchar(100)

)

Insert into #hirNode

values (1,NULL,'Start')

,(2,1,'Second')

,(3,2,'Third')

,(4,NULL,'Start2')

,(5,4,'Second2');

WITH BuildPath(hirNode,hirNodeParent, NodeLevel, NodePath)

AS (SELECT hirNode,

hirNodeParent,

1,

CONVERT(varchar(255), '\\'+Title)

FROM #hirNode

WHERE hirNodeParent IS NULL --Start at the Top

UNION ALL

SELECT

h.hirNode,

h.hirNodeParent,

NodeLevel + 1,

CONVERT (varchar(255), RTRIM(NodePath) + '\' + Title)

FROM #hirNode AS h

JOIN BuildPath AS p ON h.hirNodeParent = p.hirNode

)

Select * from BuildPath

The output for NodePath is

\\Start

\\Start\Second

\\Start\Second\Third

\\Start2

\\Start2\Second2

It might need ordering but its just an example, is that what you are looking for?