WITH ROW_ID AS(
    SELECT
        ROW_NUMBER() OVER(ORDER BY TOTAL_VALUE DESC) AS ROWID
        ,COUNT(1) OVER() AS ROWMAX
        ,PF_CODE
    FROM CONVENIENCE
    WHERE SURVEY_YEAR = 2019 AND KIND_CODE = '100'
)
SELECT ROUND(AVG(TOTAL_VALUE), 0) AS SA_MEDIAN
FROM ROW_ID NATURAL JOIN CONVENIENCE
WHERE SURVEY_YEAR = 2019 AND KIND_CODE = '100'
        AND
    ROWID BETWEEN ROWMAX /2.0 AND ROWMAX/2.0 + 1