WITH T AS (SELECT TOTAL_VALUE,  ROW_NUMBER() OVER (ORDER BY TOTAL_VALUE) AS R FROM CONVENIENCE WHERE SURVEY_YEAR = 2019 AND KIND_CODE = '100')
SELECT ROUND(AVG(TOTAL_VALUE)) AS SA_MEDIAN FROM T WHERE R BETWEEN (SELECT COUNT(*)/2.0-0.5 FROM T) AND (SELECT CASE COUNT(*)%2 WHEN 0 THEN COUNT(*)/2.0+1 ELSE COUNT(*)/2.0 END FROM T);