What was the rating/share for 18-49 for the episode that had 5.90 million viewers? 
CREATE TABLE "season_1_2010" (
  "no" real,
  "episode" text,
  "rating" text,
  "share" real,
  "rating_share_18_49" text,
  "viewers_millions" text,
  "rank_timeslot" real,
  "rank_night" real
);
SELECT "rating_share_18_49" FROM "season_1_2010" WHERE "viewers_millions"='5.90';