Calculate point in time DB Hit Ratios

-- Hit Ratio of caches

select distinct counter_name,
(select isnull(sum(convert(dec(15,0),B.cntr_value)),0) 
from master..sysperfinfo as B (nolock) 
where Lower(B.counter_name) like '%hit ratio%'
andA.counter_name = B.counter_name) as CurrHit,
(select isnull(sum(convert(dec(15,0),B.cntr_value)),0) 
from master..sysperfinfo as B (nolock) 
where Lower(B.counter_name) like '%hit ratio base%'
andlower(B.counter_name) = (lower(ltrim(rtrim(A.counter_name))) + ' base')) as CurrBase,
(select isnull(sum(convert(dec(15,0),B.cntr_value)),0) 
from master..sysperfinfo as B (nolock) 
where Lower(B.counter_name) like '%hit ratio%'
andA.counter_name = B.counter_name) / 
(select isnull(sum(convert(dec(15,0),B.cntr_value)),0) 
from master..sysperfinfo as B (nolock) 
where Lower(B.counter_name) like '%hit ratio base%'
andlower(B.counter_name) = (lower(ltrim(rtrim(A.counter_name))) + ' base')) as HitRatio
from master..sysperfinfo as A (nolock) 
where Lower(A.counter_name) like '%hit ratio%'
and Lower(A.counter_name) not like '%hit ratio base%' 

-- Audit list as a double verification

select counter_name,isnull(sum(convert(dec(15,0),cntr_value)),0) as Value
from master..sysperfinfo (nolock) 
where Lower(counter_name) like '%hit ratio%'
or Lower(counter_name) like '%hit ratio base%' 
group by counter_name