WITH tmp AS (
SELECT ROW_NUMBER() OVER(ORDER BY TOTAL_VALUE) AS RN, TOTAL_VALUE
FROM CONVENIENCE
WHERE SURVEY_YEAR=2019 AND KIND_CODE='100'
ORDER BY TOTAL_VALUE DESC
)
,
tmp2 AS (
SELECT
	CASE COUNT(*) % 2
		WHEN 1 THEN COUNT(*) / 2 + 1
		ELSE COUNT(*) / 2
	END
FROM tmp
)


SELECT ROUND(AVG(TOTAL_VALUE),0) AS SA_MEDIAN
FROM tmp
WHERE RN = (SELECT COUNT(*) / 2 FROM tmp)
   OR RN = (SELECT * FROM tmp2)