with cte as (select
*
from
convenience
where
survey_year = 2019
and
kind_code = '100'
)
select
round(avg(total_value)) as "SA_MEDIAN"
from
(select
total_value, 2 * row_number() over(order by total_value) - count(*) over() as diff 
from cte) tmp
where
diff between 0 and 2