What is the sum of number with type 0-4-4 forney locomotive, number smaller than 20 and works number of 1251?
CREATE TABLE "locomotives" (
  "number" real,
  "builder" text,
  "type" text,
  "date" real,
  "works_number" real
);
SELECT COUNT("date") FROM "locomotives" WHERE "type"='0-4-4 forney locomotive' AND "number"<20 AND "works_number"=1251;