WITH A AS(
SELECT
	TOTAL_VALUE
	,ROW_NUMBER() OVER(ORDER BY TOTAL_VALUE DESC) AS RANK
FROM
	CONVENIENCE
WHERE
	SURVEY_YEAR = 2019
	AND KIND_CODE = '100'
)
,B AS (SELECT COUNT(*) NUM FROM A)
SELECT
	CASE NUM / 2.0
		WHEN ROUND(NUM / 2) THEN (SELECT ROUND(AVG(TOTAL_VALUE)) FROM A WHERE RANK = NUM / 2 OR RANK = NUM / 2 + 1)
		ELSE (SELECT TOTAL_VALUE FROM A WHERE RANK = ROUND(NUM / 2))
	END AS SA_MEDIAN
FROM
	B
;