SQL Join for two different columns

[Chandra shekar M]

select
 unique(case  when a.val = 1 then b.type
       when a.val = 2 then c.type
       else null
  end) Type
from a
LEFT JOIN b  on a.id = b.id
LEFT JOIN c  on a.id = c.id
where
a.id in (1) and 
(c.status in (a,b,c) or b.status in (a,b,c)) and
(b.type != -99 or c.type != -99 ) 

This Query will perform joins and include records that satisfy the filtering condition in the where clause. Now even though i have a Left Join Condition on the id to pick null values 
from b and c table for a record present only in table a, it will not make to result set because status and type conditions will fail. But i need the record from table a to be returned 
for this i need to define the Join on status and Type columns too as i have done for id column. But table a doesnt have Status and Type column. How can i write query to solve this issue?

[Koen Aerts]

Did you try an OUTER join (default is INNER):
LEFT OUTER JOIN b on a.id = b.id
LEFT OUTER JOIN c on a.id = c.id

[Chandra shekar M]

Hi Koen,
Thanks for the reply. Ouetr join doesnt made any difference. I rewrote the Query like below

select  
 unique(case  when a.val = 1 then b.type  
       when a.val = 2 then c.type  
       else null  
  end) Type  
from a  
LEFT JOIN (select * from b where b.type != -99 and b.status in (a,b,c))  on a.id = b.id  
LEFT JOIN  (select * from c where c.type != -99 and c.status in (a,b,c))  on a.id = c.id  
where  a.id in (1)    

The Problem was.
1. First the join was made and then filtering. Filtering logic was specific to the tables b,c and even the joined records use to get dropped off.
Solution
First put the Filtering logic specific to tables b, c before join and then do the generic filtering on the joined records.

This solves the issue.

Thanks
Chandra