What was the previous conference for the school that joined in 2000 with a millers mascot?
CREATE TABLE "member_schools" (
  "school" text,
  "location" text,
  "mascot" text,
  "county" text,
  "2013_2014_size" real,
  "year_joined" real,
  "previous_conference" text
);
SELECT "previous_conference" FROM "member_schools" WHERE "year_joined"=2000 AND "mascot"='millers';