What's the Time for an Event of 4x100 m relay and has a Venue of Frankfurt?
CREATE TABLE "achievements" (
  "year" real,
  "competition" text,
  "venue" text,
  "position" text,
  "event" text,
  "time" text
);
SELECT "time" FROM "achievements" WHERE "event"='4x100 m relay' AND "venue"='frankfurt';