select round(avg(total_value)) as SA_MEDIAN from 
( select total_value from convenience
where survey_year = 2019 and kind_code = '100'
order by total_value
limit ((select count(*) from convenience where survey_year = 2019 and kind_code = '100')-1)/2,
(select count(*) from convenience where survey_year = 2019 and kind_code = '100')-((select count(*) from convenience where survey_year = 2019 and kind_code = '100')-1)/2*2);