SELECT
    ROUND(AVG(TOTAL_VALUE)) AS SA_MEDIAN
FROM
    (
        SELECT
            TOTAL_VALUE
        FROM
            CONVENIENCE
        ORDER BY
            TOTAL_VALUE
        LIMIT 2 - (
            SELECT
                COUNT(*)
            FROM
                CONVENIENCE
        ) % 2
        OFFSET(
            SELECT
                (COUNT(*) - 1) / 2
            FROM
                CONVENIENCE
        )
    )
;