CREATE TABLE table_203_475 (id NUMBER, "stage" NUMBER, "date" CLOB, "route" CLOB, "terrain" CLOB, "length" CLOB, "winner" CLOB)

how much longer is the 20th tour de france stage than the 19th ?
SELECT (SELECT "length" FROM table_203_475 WHERE "stage" = 20) - (SELECT "length" FROM table_203_475 WHERE "stage" = 19)
SELECT (SELECT "length" FROM "table_203_475" WHERE "stage" = 20) - (SELECT "length" FROM "table_203_475" WHERE "stage" = 19)