How to reference LEVEL in a TREE's SQL code

Question

Is it possible to somehow reference LEVEL in a tree's sql code so that you can use a decode statement to selectively create links on specific levels only i.e. NOT on the root level?
e.g.
select "CHILD_ID" id,
"PARENT_ID" pid,
"NAME" name,
decode( LEVEL, 1, null,'f?p=' || :APP_ID || ':43:' || :APP_SESSION || '::::P43_CHILD_ID:' || CHILD_ID) link,
null a1,
null a2
from TREETABLE
order by name
one solution I've implemented is to create a DB function e.g.
create or replace function get_tree_level(v_child_id number) return number
is
v_level number(2);
begin
select level
into v_level
from TREETABLE
where child_id=v_child_id
start with child_id=1
connect by prior child_id= parent_id;
return v_level;
end;
and then use
decode( get_tree_level(child_id) 1, null,'f?p=' || :APP_ID || ':43:' || :APP_SESSION || '::::P43_CHILD_ID:' || CHILD_ID) link,
but this is too slow as I have quite a few records in the tree and takes too long to render
regards
Paul P

Answer 1

OK I found a workaround after reading
How to add URL to tree
The view my tree is build on is constructed out of 3 unions and 4 "selects" ( the first select creates the ROOT NODE where "1" is also used as a hard coded foreign key (Parent_id), in the company table.)
I just added a new column called tree_level to the query which is hard coded wrt its level on the hierarchy.
e.g.
CREATE OR REPLACE FORCE VIEW COMCONSTUTREE ("CHILD_ID", "PARENT_ID", "NAME","TREE_LEVEL") AS
select 1 as child_id,to_number(null) as parent_id ,'Company' as name,*1 as tree_level* from dual
UNION
select COM_ID, 1, COM_NAME,2
from company
UNION
select CON_ID,CON_COMPANY_ID, substr(con_name,instr(con_name,' ')+1) ||', '||substr(con_name,1,instr(con_name,' ')-1),3
from contact
UNION
select STU_ID,STU_CONTACT_ID, STU_LAST_NAME||', '||STU_FIRST_NAME ,4
from student;
the tree code now becomes
select "CHILD_ID" id,
"PARENT_ID" pid,
"NAME" name,
decode( tree_level,1, null,'f?p=' || :APP_ID || ':43:' || :APP_SESSION || ':TREE:::P43_CHILD_ID:' ||CHILD_ID) link,
null a1,
null a2
from COMCONSTUTREE"
order by name