Query needed for the below requirement

Question

Hi,
I have three tables structures like below.
tableA - LINE_ID, VENDOR_ID,DEAL_SITE_ID
tableB - LINE_ID, DEAL_SITE_ID
tableC - DEAL_ID,VERSION, DEAL_SITE_ID
Now the requirement is I have to fetch all distinct VENDOR_ID from tableA with some given DEAL_ID (100001) and VERSION (1), only Problem is in tableA the rows which have LINE_ID will not have DEAL_SITE_ID and vice versa. I've used the below query for this purpose but wanted to know if there is any better solution.
select distinct VENDOR_ID from tableA where deal_site_id in
(select deal_site_id from tableC where deal_id = 100001 and snapshot_ver = 1)
UNION
select distinct VENDOR_ID from tableA where line_id in
(select line_id from tableB where deal_site_id in
(select deal_site_id from tableC where deal_id = 100001 and snapshot_ver = 1))
Regards,
Subhadeep
Edited by: sumajumd on Jul 17, 2012 2:33 AM

Answer 1

Try regular joins (assuming column version should be snapshot_ver).
Like this (untested):
select tablea.vendor_id
from   tablea
  inner join tablec on (tablea.deal_site_id = tablec.deal_site_id)
where  tablec.deal_id      = 100001
and    tablec.snapshot_ver = 1
union
select tablea.vendor_id
from   tablea
  inner join tableb on (tableb.line_id      = tablea.line_id)
  inner join tablec on (tableb.deal_site_id = tablec.deal_site_id)
where  tablec.deal_id      = 100001
and    tablec.snapshot_ver = 1