WITH RANK_T AS (
    SELECT
        RANK() OVER(ORDER BY TOTAL_VALUE DESC) AS RANK,
        TOTAL_VALUE
    FROM
        CONVENIENCE
    WHERE
        SURVEY_YEAR = '2019'
        AND
        KIND_CODE = '100'
)

SELECT
    ROUND(
        CASE MOD(COUNT(*), 2)
            WHEN  1 THEN (
                SELECT
                    AVG(TOTAL_VALUE)
                FROM
                    RANK_T R2
                WHERE
                    RANK = (SELECT COUNT(*) FROM RANK_T) / 2 + 1
            )
            ELSE (
                SELECT
                    AVG(TOTAL_VALUE)
                FROM
                    RANK_T R2
                WHERE
                    RANK = (SELECT COUNT(*) FROM RANK_T) / 2
                OR
                    RANK = (SELECT COUNT(*) FROM RANK_T) / 2 + 1
            )
        END
    , 0) AS SA_MEDIAN
FROM
    RANK_T R1
;