CREATE TABLE "production_overview" (
  "pilot_car_no" real,
  "colour" text,
  "serial_no" text,
  "engine_no" real,
  "registration_no" text
);

Question: What is the number of colour with the regisration number of mg-509?
SQL: SELECT COUNT("colour") FROM "production_overview" WHERE "registration_no"='MG-509';