with total as (
    select total_value as v
            from convenience
            where kind_code = '100'
            and survey_year = '2019'
) ,
median as (
    select round( count(v) * 0.5) as c from total
    
)
select 
    round( 
        (  select max(v) from ( select v from total order by v asc limit ( select c from median) ) )
        +   (  select min(v) from ( select v from total order by v desc limit ( select c from median) ) ) 
        * 0.5
    , 0 )   as SA_MEDIAN