CREATE TABLE "table1_21550897_1" (
  "no" real,
  "num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "u_s_viewers_million" text,
  "original_air_date" text,
  "production_code" real
);

Question: How many times did episode 6 originally air?
SQL: SELECT COUNT("original_air_date") FROM "table1_21550897_1" WHERE "num"=6;

Question: What is the production code for the episode that had 9.18 million viewers (U.S.)?
SQL: SELECT MAX("production_code") FROM "table1_21550897_1" WHERE "u_s_viewers_million"='9.18';

Question: What episode number was directed by Craig Ross, Jr.
SQL: SELECT "num" FROM "table1_21550897_1" WHERE "directed_by"='Craig Ross, Jr.';

Question: What episode had 10.14 million viewers (U.S.)?
SQL: SELECT MIN("num") FROM "table1_21550897_1" WHERE "u_s_viewers_million"='10.14';

Question: Who wrote the episode with the production code 519?
SQL: SELECT "written_by" FROM "table1_21550897_1" WHERE "production_code"=519;