What is the total of yards when asst. is 19, totaltk is 60 and sack is more than 0?
CREATE TABLE "defense" (
  "player" text,
  "tackles" real,
  "asst" real,
  "total_tk" real,
  "sack" real,
  "yards" real,
  "fum_r" real
);
SELECT SUM("yards") FROM "defense" WHERE "asst"=19 AND "total_tk"=60 AND "sack">0;