SQL & PL/SQL :: Giving START WITH Dynamically In A Query

How do you specify the value in START WITH dynamically during runtime. For example consider the bewlo scenario:

CREATE TABLE ISCT
(
ITEM_NO VARCHAR2(15 CHAR) NOT NULL,
ITEM_TYPE VARCHAR2(3 CHAR) NOT NULL,
ITEM_TYPE_SCO VARCHAR2(3 CHAR) NOT NULL,

[Code].....

Now if you create a view:

create or replace view test_v
(ITEM_NO, ITEM_TYPE, ITEM_NO_SCO,ITEM_TYPE_SCO)
as
SELECT T.ITEM_NO, T.ITEM_TYPE, CONNECT_BY_ROOT T.ITEM_NO_SCO,T.ITEM_TYPE_SCO
FROM
[Code] .......

Then run the below query:

select * from test_v where item_no_sco = '00245905'
--

the output is got within a second. but the real scenario is that both table icont and isct have millions of rows. In that case even this small query of the view takes 10minutes as there a FULL TABLE JOIN.

How do I give the START WITH in the view to make it faster i.e. even with millions of rows the output of this comes in seconds:

SELECT T.ITEM_NO, T.ITEM_TYPE, CONNECT_BY_ROOT T.ITEM_NO_SCO,T.ITEM_TYPE_SCO
FROM
(
SELECT NVL(C.ITEM_NO_CHILD, I.ITEM_NO) ITEM_NO, NVL(C.ITEM_TYPE_CHILD,
I.ITEM_TYPE) ITEM_TYPE, I.ITEM_TYPE_SCO, I.ITEM_NO_SCO
[Code] .......

MC: Remove code tags on INSERT, CM take care to not exceed 80 characters when you add coce tags: reformat yourself or do not do it.