CREATE TABLE "table1_15431959_1" (
  "no_in_season" real,
  "no_disc" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text
);

Question: What was the original air date of Stargate SG-1 written by Peter Deluise?
SQL: SELECT "original_air_date" FROM "table1_15431959_1" WHERE "written_by"='Peter DeLuise';

Question: How many seasons did Peter Deluise direct Stargate SG-1?
SQL: SELECT MAX("no_in_season") FROM "table1_15431959_1" WHERE "directed_by"='Peter DeLuise';

Question: Which number episode of season 6 was the title "Sight Unseen"?
SQL: SELECT MIN("no_in_season") FROM "table1_15431959_1" WHERE "title"='\"Sight Unseen\"';