SQL & PL/SQL

Hi, I have two issues, here is my initial code:

select
cc.name_id_no
,cc.discover_date
,cc.cla_case_no
,max(rl.year_of_incident)Non_Loss_Past_5
,rl.timestamp
from cla_case cc, rbn_loss rl
where cc.name_id_no = rl.customer_no
and rl.year_of_incident < trunc(cc.discover_date)
and rl.type_of_loss < 1000
and rl.timestamp < trunc(cc.discover_date)
and (cc.question_class = 20
or cc.question_class = 25)
and (trunc(cc.discover_date)- (rl.year_of_incident)) < 1095
--and (trunc(cc.discover_date) <> (rl.year_of_incident))
group by cc.cla_case_no,name_id_no, cc.discover_date,rl.timestamp

Now a cla_case_no can map to several year_of_incident. I only want the cla_case_no that maps to the max year_of_incident ie There should only be a single cla_case_no corresponding to the max year_of_incident.

To get around this I did the following which is not very efficient and I'm hoping it can be improved:

select distinct z.cla_case_no from (

select
cc.name_id_no
,cc.discover_date
,cc.cla_case_no
,max(rl.year_of_incident)Non_MW_Loss_Past_5
,rl.timestamp
from cla_case cc, rbn_loss rl
where cc.name_id_no = rl.customer_no
and rl.year_of_incident < trunc(cc.discover_date)
and rl.type_of_loss < 1000
and rl.timestamp < trunc(cc.discover_date)
and (cc.question_class = 20
or cc.question_class = 25)
and (trunc(cc.discover_date)- (rl.year_of_incident)) < 1095
--and (trunc(cc.discover_date) <> (rl.year_of_incident))
group by cc.cla_case_no,name_id_no, cc.discover_date,rl.timestamp
) z

Now comes the second issue: The above is actually a subquery that will link to a bigger table via cla_case_no ccx

SELECT

ie ,(select distinct z.cla_case_no from (

select cc.name_id_no, cc.discover_date ,cc.cla_case_no, max(rl.year_of_incident)Non_MW_Loss_Past_5, rl.timestamp
from cla_case cc, rbn_loss rl
where cc.name_id_no = rl.customer_no
and rl.year_of_incident < trunc(cc.discover_date)
and rl.type_of_loss < 1000
and rl.timestamp < trunc(cc.discover_date)
and (cc.question_class = 20
or cc.question_class = 25)
and (trunc(cc.discover_date)- (rl.year_of_incident)) < 1095
--and (trunc(cc.discover_date) <> (rl.year_of_incident))
group by cc.cla_case_no,name_id_no, cc.discover_date,rl.timestamp
) z
where z.cla_case_no = ccx.cla_case_no
) Non_MW_Loss_Past_5

FROM etc

Now only certain cc.cla_case_no from the subquery will corresp to the ccx_cla_case_no from the main table and the other entries will be null.

What I require is that if the subquery returns a result that IS NOT NULL to return 'Y' ELSE 'N' instead of the varies cla_case_no's and (null) entries in the Non_MW_Loss_Past_5 column

Thanks!!!

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