On what date of polling was the Polling Firm forum research with 7 green and less than 30 liberals?
CREATE TABLE "opinion_polls" (
  "polling_firm" text,
  "date_of_polling" text,
  "link" text,
  "liberal" real,
  "green" real
);
SELECT "date_of_polling" FROM "opinion_polls" WHERE "polling_firm"='forum research' AND "green"=7 AND "liberal"<30;