Which Small (100ha) is the highest one that has a Big (>500ha) larger than 9,021?
CREATE TABLE "irrigation_infrastructure" (
  "department" text,
  "micro_10ha" real,
  "small_100ha" real,
  "medium_500ha" real,
  "big_500ha" real,
  "total" real
);
SELECT MAX("small_100ha") FROM "irrigation_infrastructure" WHERE "big_500ha">'9,021';