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(*)+1)/2 FROM T) AND (SELECT CASE COUNT(*)%2 WHEN 0 THEN (COUNT(*)+1)/2+1 ELSE (COUNT(*)+1)/2 END FROM T);