What is the district where Steve Carriker is the Democratic Senator and he took office later than 1988?
CREATE TABLE "senate" (
  "senator" text,
  "party" text,
  "district" real,
  "home_town" text,
  "took_office" real
);
SELECT MAX("district") FROM "senate" WHERE "party"='democratic' AND "senator"='steve carriker' AND "took_office">1988;