with t1 as(
select TOTAL_VALUE, row_number() over (order by TOTAL_VALUE) as rank
from CONVENIENCE
where SURVEY_YEAR = 2019 and KIND_CODE = '100'
)
-- max(rank) の偶奇で分ける
-- select max(rank) / 2, max(rank) / 2 +1 from t1
-- select 
--     *,
--     CASE WHEN max(rank) % 2 = 0 THEN 
--         (SELECT TOTAL_VALUE FROM t1 where rank = FLOOR(max(rank) / 2)
--     ELSE 0
--     END as flg
-- from t1
select 
    ROUND(AVG(TOTAL_VALUE))
from t1 -- 35
where rank between (
    select floor(max(rank) * 1.0 / 2) from t1
    ) and (
    select floor(max(rank) * 1.0 / 2 + 1) from t1
    )