select
    avg(TOTAL_VALUE) as SA_MEDIAN
from
(
select
    TOTAL_VALUE
    ,row_number() over(partition by '' order by TOTAL_VALUE) as RN
    ,row_number() over(partition by '' order by TOTAL_VALUE)+0.5 as RN01
    ,row_number() over(partition by '' order by TOTAL_VALUE)-0.5 as RN02
from
    CONVENIENCE
where
    SURVEY_YEAR='2019'
    and KIND_CODE='100'
) SUB
where
    RN in (select count(*)/2 from CONVENIENCE where SURVEY_YEAR='2019' and KIND_CODE='100')
    or 
    RN01 in (select count(*)/2 from CONVENIENCE where SURVEY_YEAR='2019' and KIND_CODE='100')
    or
    RN02 in (select count(*)/2 from CONVENIENCE where SURVEY_YEAR='2019' and KIND_CODE='100')
;