Strange behaviour of hierarchical query

Question

Hi,
there is two tables T(P,PK,...) (with hierarchy) and S(ID,IDS,....) with additional data.
I take query:
select S.IDS from T, S
where T.PK=S.ID
start with P=start number
connect by prior PK=P
Query work fine and return rows ...
but when I add another where condition
select S.IDS from T, S
where T.PK=S.ID and S.IDS=searched number
start with P=start number
connect by prior PK=P
query do not return rows even when searched number is in set returned by first query without additional condition.
It seems to me strange ... thanks for idea

Answer 1

Hi,
The subquery match's the outer query rows.
In this event the IN condition returns FALSE. Hence the query runs with out any error.
As IN is concern the condition will look for True Or False Only.Error will happen only if any syntax issue else the query will still run.
you can mention any coulmn name of outer query in subquery eventhough they dont exisit , the inner query can reference the outer query's column names.
I hope you are clear on this...........
Raj.
Edited by: infant_raj on May 4, 2009 7:44 AM