with T as (select KIND_CODE,
                  PF_CODE,
                  rank() over ( ORDER BY TOTAL_VALUE ,KIND_CODE, PF_CODE
                      ) - 1 as rnk
           from CONVENIENCE
           where SURVEY_YEAR = 2019
             and KIND_CODE = '100')
   , T2 as (select count(*) as CO from CONVENIENCE where SURVEY_YEAR = 2019 and KIND_CODE = '100')

select round(avg(CONVENIENCE.TOTAL_VALUE),0) SA_MEDIAN
from CONVENIENCE
         inner join T on CONVENIENCE.PF_CODE = T.PF_CODE and
                         CONVENIENCE.KIND_CODE = T.KIND_CODE
   , T2
where CONVENIENCE.SURVEY_YEAR = 2019
  and CONVENIENCE.KIND_CODE = '100'
  and ((t2.co % 2 = 0 and rnk in (t2.co / 2, t2.co / 2 - 1)) or (t2.co % 2 = 1 and rnk = t2.co / 2))