Name the least points where 1989-90 is 31
CREATE TABLE "relegation" (
  "team" text,
  "average" text,
  "points" real,
  "played" real,
  "1989_90" text,
  "1990_91" text,
  "1991_1992" real
);
SELECT MIN("points") FROM "relegation" WHERE "1989_90"='31';