WITH t AS (
    SELECT
        TOTAL_VALUE	
        ,row_number() over(order by TOTAL_VALUE) as rn
    FROM
        CONVENIENCE
    WHERE
        SURVEY_YEAR = 2019
        AND KIND_CODE = 100
), m as(
    SELECT MAX(rn) FROM t
),tmp AS(
    SELECT
        TOTAL_VALUE
        ,CASE
            WHEN (select * from m) % 2 = 0 AND(rn = (select * from m)/2 or rn = (select * from m)/2 + 1) THEN 1
            WHEN (select * from m) % 2 = 1 AND(rn = ((select * from m)-1)/2 + 1) THEN 1
            ELSE 0
            END AS flg
    FROM t
)
-- select *from tmp
select ROUND(AVG(TOTAL_VALUE)) AS SA_MEDIAN from tmp where flg = 1