Firebird 3.0

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create table T (NodeID integer, ParentNodeID integer, Name varchar(30))
insert into t values (1, -1, 'Parent');
1 rows affected

insert into t values (2, 1, 'Child');
1 rows affected

insert into t values (3, 2, 'Child of child');
1 rows affected

create procedure tree (root integer) returns (result varchar(1000)) as
  declare id integer;
  declare n varchar(30);
  declare childs varchar(1000);
begin
  for select NodeId, Name from t where ParentNodeId = :root order by Name into :id, :result do
   begin
    suspend;
    n = result;
    for select result from tree(:id) into :childs do
      begin
        result = n || ' - ' || childs;
        suspend;
      end
   end
end
select * from tree(-1)


RESULT


Parent

Parent - Child

Parent - Child - Child of child