Using Arithmetic in SQL on my own columns to fill a third column where it is zero., Sql Server

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create table t (
    CountyID int
  , IndustryID int
  , [Year] int
  , Qtr int
  , Suppressed int
  , Data_Cat int
  , Data_Denom int
  , [Value] int
);
insert into t values
 (5,10,1990,1,1,1,1,0)
,(5,10,1990,1,1,1,2,0)
,(5,10,1990,1,1,1,3,0)
,(5,10,1991,1,0,1,1,5)
,(5,10,1991,1,0,1,2,15)
,(5,10,1991,1,0,1,3,25)
,(5,10,1991,1,0,3,1,20)
,(5,10,1991,1,0,3,2,20)
,(5,10,1991,1,0,3,3,35);

select t.*
  , NewValue = cat3.value - cat1.value
from t
cross apply (
    select i.value 
    from t as i
    where i.CountyID     = t.CountyID
      and i.IndustryID   = t.IndustryID
      and i.Data_Denom = t.Data_Denom 
      and i.Year = t.Year +1
      and i.Qtr  = t.Qtr
      and i.Suppressed = 0
      and i.Data_Cat   = 1

) cat1
cross apply (
    select i.value 
    from t as i
    where i.CountyID     = t.CountyID
      and i.IndustryID   = t.IndustryID
      and i.Data_Denom = t.Data_Denom 
      and i.Year = t.Year +1
      and i.Qtr  = t.Qtr 
      and i.Suppressed = 0
      and i.Data_Cat   = 3
) cat3
where t.Suppressed = 1
  and t.Data_Cat   = 1
  
select t.*
  , NewValue = coalesce(nullif(t.value,0),cat3.value - cat1.value,0)
from t
outer apply (
    select i.value 
    from t as i
    where i.CountyID     = t.CountyID
      and i.IndustryID   = t.IndustryID
      and i.Data_Denom = t.Data_Denom 
      and i.Year = t.Year +1
      and i.Qtr  = t.Qtr
      and i.Suppressed = 0
      and i.Data_Cat   = 1

) cat1
outer apply (
    select i.value 
    from t as i
    where i.CountyID     = t.CountyID
      and i.IndustryID   = t.IndustryID
      and i.Data_Denom = t.Data_Denom 
      and i.Year = t.Year +1
      and i.Qtr  = t.Qtr
      and i.Suppressed = 0
      and i.Data_Cat   = 3
) cat3

View schema
Execution time: 0,03 sec, rows selected: 12, rows affected: 9, absolute service time: 0,19 sec

Using Arithmetic in SQL on my own columns to fill a third column where...