investigation.sql

select s1.d, n1, n2, cast(n2 as decimal) / cast(n1 as decimal)
from
(
        select d, count(*), n1 from (
                select convert(varchar(7), admission_date, 23) d
                from apcs_cost c
                join apcs a
                        on c.apcs_ident = a.apcs_ident
        ) s
        group by d
) s1
join
(
        select d, count(*), n1 from (
                select convert(varchar(7), admission_date, 23) d
                from apcs_cost_jrc20231009_lastfilestocontainallhistoricalcostdata c
                join apcs_jrc20231009_lastfilestocontainallhistoricalcostdata a
                        on c.apcs_ident = a.apcs_ident
        ) s
        group by d
) s2
on s1.d = s2.d
order by d

Where's n2 coming from, or should L14 read n2 instead of n1?