CASE Statement inside a subquery - sql

Question

I was able to create the following query after help from the post below
select * from duppri t
where exists (
select 1
from duppri
where symbolUP = t.symbolUP
AND date = t.date
and price <> t.price)
ORDER BY date
SQL to check when pairs don't match
I have now realized that I need to add a case statement to indicate when all the above criteria fits, but the type value is equal between duppri and t.duppri. This occurs because of case sensitivity. This query is an attempt to clean up a portfolio accounting system that unfortunately allowed numerous duplicates because it didn't have strong referential integrity or constraints.
I would like the case statement to produce the column 'isMatch'
Date |Type|Symbol |SymbolUP |Concatt |Price |IsMatch
6/30/1995 |gaus|313586U72|313586U72|gaus313586U72|109.25|Different
6/30/1995 |gbus|313586U72|313586U72|gbus313586U72|108.94|Different
6/30/1995 |agus|SRR |SRR |agusSRR |10.25 |Different
6/30/1995 |lcus|SRR |SRR |lcusSRR |0.45 |Different
11/27/1996|lcus|LLY |LLY |lcusLLY |76.37 |Matched
11/27/1996|lcus|lly |LLY |lcusLLY |76 |Matched
11/28/1996|lcus|LLY |LLY |lcusLLY |76.37 |Matched
11/28/1996|lcus|lly |LLY |lcusLLY |76 |Matched
I tried the following CASE statement but it is creating errors
SELECT * from duppri t
where exists (
select 1,
CASE IsMatch WHEN [type] = [t.TYPE] THEN 'Matched' ELSE 'Different' END
from duppri
where symbolUP = t.symbolUP
AND date = t.date
and price <> t.price)
ORDER BY date

Answer 1

You could just use window functions, if I understand correctly:
select d.*,
(case when mint = maxt
then 'Matched' else 'Different'
end)
from (select d.*,
min(type) over (partition by symbolup, date) as mint,
max(type) over (partition by symbolup, date) as maxt,
min(price) over (partition by symbolup, date) as minp,
max(price) over (partition by symbolup, date) as maxp
from duppri d
) d
where minp <> maxp
order by date;

Answer 2

The subquery used with the exists predicate can't and won't return anything other than true/false but you can accomplish what you want using a subquery like this, which should work:
select
*,
(select
CASE when count(distinct type) = 1 THEN 'Matched' ELSE 'Different' END
from duppri
where symbol = t.symbol and date = t.date
) IsMatch
from duppri t
where exists (
select 1
from duppri
where symbol = t.symbol
and price <> t.price);