with T1 AS 
(
SELECT
ROW_NUMBER() OVER(ORDER BY TOTAL_VALUE DESC) AS ROWNUM,
TOTAL_VALUE
FROM
CONVENIENCE
WHERE
SURVEY_YEAR = '2019'
AND
KIND_CODE = '100'
ORDER BY TOTAL_VALUE DESC
)

SELECT
(
  CASE
    WHEN max % 2 = 0 
    THEN 
    (
        SELECT 
        ROUND(AVG(T1.TOTAL_VALUE),0)
        FROM T1 
        WHERE 
        T1.ROWNUM = max/2
        OR
        T1.ROWNUM = (max/2) + 1
    )
    ELSE
    (
        SELECT 
        T1.TOTAL_VALUE
        FROM T1
        WHERE
        T1.ROWNUM = ROUND(max/2,0)
    )
    END
)
AS SA_MEDIAN
FROM
(SELECT 
MAX(T1.ROWNUM) AS max,
T1.TOTAL_VALUE
FROM T1)