Select all parents or children in same table relation SQL Server

Question

SQL developers, I have a badly planned database as task to learn a lot about SQL Server 2012.

SO, there is the table Elem:

+-----------+----         


        

Answer 1

here is a recursive query giving you both all ancestors and all descendants of an element. Use these together or separate according to the situation. Replace the where clauses to get the desired record. In this example I am looking for key 13 (this is the element with name = b) and find its ancestor 12/a and its descendant 14/c.

with all_ancestors(relation, version, name, elem_key, parent_key, dist_key)
as 
(
  -- the record itself
  select 'self      ' as relation, self.version, self.name, self.elem_key, self.parent_key, self.dist_key
  from elem self
  where elem_key = 13
  union all
  -- all its ancestors found recursively
  select 'ancestor  ' as relation, parent.version, parent.name, parent.elem_key, parent.parent_key, parent.dist_key
  from elem parent
  join all_ancestors child on parent.elem_key = child.parent_key
)
, all_descendants(relation, version, name, elem_key, parent_key, dist_key)
as 
(
  -- the record itself
  select 'self      ' as relation, self.version, self.name, self.elem_key, self.parent_key, self.dist_key
  from elem self
  where elem_key = 13
  union all
  -- all its descendants found recursively
  select 'descendant' as relation, child.version, child.name, child.elem_key, child.parent_key, child.dist_key
  from elem child
  join all_descendants parent on parent.elem_key = child.parent_key
)
select * from all_ancestors
union
select * from all_descendants
order by elem_key
;

Here is the SQL fiddle: http://sqlfiddle.com/#!6/617ee/28.