What is the Badge/Serial Number of the Policeman who died in Gunfire on 1919-02-18?
CREATE TABLE "officers" (
  "rank" text,
  "badge_serial_number" text,
  "tenure" text,
  "date_of_death" text,
  "cause_of_death" text
);
SELECT "badge_serial_number" FROM "officers" WHERE "rank"='policeman' AND "cause_of_death"='gunfire' AND "date_of_death"='1919-02-18';