Oracle Hierarchical queries with views and joins - sql

Question

I have a table setup like this:
create table DEP
(
depid NUMBER,
name VARCHAR2(200),
manager NUMBER
);
create table EMP
(
empid NUMBER,
depid NUMBER,
name VARCHAR2(200),
role VARCHAR2(200),
salary NUMBER,
manager NUMBER
);
insert into dep (DEPID, NAME, MANAGER)
values (1, 'IT', 2);
insert into dep (DEPID, NAME, MANAGER)
values (2, 'ACCOUNTING', 4);
insert into dep (DEPID, NAME, MANAGER)
values (3, 'MARKETING', 5);
insert into emp (EMPID, DEPID, NAME, ROLE, SALARY, MANAGER)
values (1, 1, 'KEVIN', 'PROGRAMMER', 20000, 2);
insert into emp (EMPID, DEPID, NAME, ROLE, SALARY, MANAGER)
values (2, 1, 'LOUIS', 'ANALYST', 30000, null);
insert into emp (EMPID, DEPID, NAME, ROLE, SALARY, MANAGER)
values (3, 2, 'RACHEL', 'CASHER', 15000, 4);
insert into emp (EMPID, DEPID, NAME, ROLE, SALARY, MANAGER)
values (4, 2, 'JOHN', 'ECONOMIST', 50000, null);
insert into emp (EMPID, DEPID, NAME, ROLE, SALARY, MANAGER)
values (5, 3, 'ERNEST', 'WRITER', 22000, null);
insert into emp (EMPID, DEPID, NAME, ROLE, SALARY, MANAGER)
values (6, 3, 'JACK', 'COMMUNITY MANAGER', 18000, 5);
Then I create these two equivalent views
create or replace view depemp1 as
with v as (
select emp.empid, dep.depid, dep.name depname, emp.name, emp.role, emp.salary,emp.manager
from emp, dep
where emp.depid = dep.depid
)
select v1.empid v1_empid, v1.depid v1_depid, v1.depname v1_depname, v1.name v1_name, v1.role v1_role, v1.salary v1_salary,v1.manager v1_manager
,v2.empid v2_empid, v2.depid v2_depid, v2.depname v2_depname, v2.name v2_name, v2.role v2_role, v2.salary v2_salary,v2.manager v2_manager
from v v1 ,v v2
where v1.empid = v2.empid
create or replace view depemp2 as
select emp1.empid v1_empid, dep1.depid v1_depid, dep1.name v1_depname, emp1.name v1_name, emp1.role v1_role, emp1.salary v1_salary,emp1.manager v1_manager
,emp2.empid v2_empid, dep2.depid v2_depid, dep2.name v2_depname, emp2.name v2_name, emp2.role v2_role, emp2.salary v2_salary,emp2.manager v2_manager
from emp emp1, emp emp2, dep dep1, dep dep2
where emp1.depid = dep1.depid and emp2.depid = dep2.depid
and emp2.empid = emp1.empid
If I select from them I can check it.
select * from depemp1;
select * from depemp2;
Now lets consider the next query to depemp1:
select
level,
depemp1.*
from depemp1
connect by prior v1_empid = v1_manager
start with v1_manager is null
The query above gives no result. Nevertheless, the same query to depemp2 (that gives the same rows and data than depemp1) gives 6 rows.
select
level,
depemp2.*
from depemp2
connect by prior v1_empid = v1_manager
start with v1_manager is null
I am using Oracle 10g and I don't understand why is this behaviour. I think this hierarchical query works on the same data output from depemp1 and depemp2 and should give the same result.