with tbl as (
    select 
        row_number() over(order by total_value desc) as row_num,
        total_value 
    from convenience 
    where survey_year=2019 and kind_code=100
),cnt as (
    select 
        count(*),
        count(*) % 2 as mod,
        case count(*) % 2 
            when 0 then count(*)/2
            else count(*)/2+1
        end as tgtrow2,
        count(*)/2+1 as tgtrow1 
    from tbl
)
select 
    case cnt.mod 
        when 0 then round(avg(tbl.total_value) ,0)
        else tbl.total_value 
    end as SA_MEDIAN 
from tbl 
cross join cnt 
where row_num in (cnt.tgtrow1,tgtrow2)
;