How many dates are there in round 3?
CREATE TABLE "race_calendar_and_results" (
  "round" text,
  "circuit" text,
  "date" text,
  "pole_position" text,
  "fastest_lap" text,
  "winning_driver" text,
  "winning_team" text
);
SELECT COUNT("date") FROM "race_calendar_and_results" WHERE "round"='3';