CREATE TABLE "calendar" (
  "round" real,
  "circuit" text,
  "date" text,
  "pole_position" text,
  "fastest_lap" text,
  "winning_drivers" text,
  "winning_team" text
);

Question: On how many different dates was the race at the Silverstone circuit?
SQL: SELECT COUNT("date") FROM "calendar" WHERE "circuit"='Silverstone';

Question: When was the circuit Donington Park?
SQL: SELECT "date" FROM "calendar" WHERE "circuit"='Donington Park';