Hierarchical queries and referential constraints

Question

Experts,
What is the rationale for having a referential integrity constraint on a table that has rows bound by hierarchical relationships ?? The hierarchical relationship ensures that each row is referencing another in the same table via the PRIOR clause. If I add a foreign key relationship to these columns , does it make any sense ??/
-Rekha

Answer 1

but you can use a hierarchical query to display constraints in a tree !
SQL> create table t1 (a number primary key);
Table created.
SQL> create table t2 (b number primary key, a number references t1(a));
Table created.
SQL> create table t3 (c number primary key, b number references t2(b));
Table created.
SQL> create table t4 (d number primary key, a number references t1(a));
Table created.
SQL> create table t5 (e number primary key, f number references t5(e));
Table created.
SQL> select sys_connect_by_path(p.table_name,':')||':'||r.table_name p
from all_constraints p
    join all_constraints r
    on (p.constraint_name = r.r_constraint_name and p.owner = r.r_owner)
where CONNECT_BY_ISLEAF = 1
connect by nocycle prior r.table_name = p.table_name
start with p.table_name not in (select r.table_name from all_constraints p join
all_constraints r on (p.constraint_name = r.r_constraint_name and
p.owner = r.r_owner and p.table_name != r.table_name) );
:DEPT:EMP
:T1:T4
:T1:T2:T3
:T5:T5