Find all leaf node records using hierarchyid

Question

How would I go about querying for only records that are "only leaf nodes" (ie. no children)?

I have tried a query like this:

select *
from TableA tt
where tt.HierarchyId.GetDescendant(null, null) not in 
(
    Select  t.HierarchyId
    from TableA t
)

But this still seemed to return some nodes that had children.

I am using the built-in hierarchyid data type (part of ms sqlserver)

Answer 1

SELECT A.HieracrchyId, A.HierarchyId.ToString()
  FROM dbo.TableA AS A 
  LEFT OUTER JOIN dbo.TableA AS B
  ON A.HierarchyId = B.HierarchyId.GetAncestor(1)
  WHERE B.HierarchyId IS NULL;