CREATE TABLE table_204_127 (id DECIMAL, "outcome" TEXT, "no." DECIMAL, "date" TEXT, "tournament" TEXT, "surface" TEXT, "opponent" TEXT, "score" TEXT)

which surface was played on the least ?
SELECT "surface" FROM table_204_127 GROUP BY "surface" ORDER BY COUNT(*) LIMIT 1
SELECT "surface" FROM "table_204_127" GROUP BY "surface" ORDER BY COUNT(*) NULLS FIRST LIMIT 1