CREATE TABLE "by_population" (
  "rank" real,
  "province" text,
  "population" real,
  "area" real,
  "density" real
);

Question: WHat is the number of Population has a Density of 50.09 and a Rank larger than 30?
SQL: SELECT SUM("population") FROM "by_population" WHERE "density"=50.09 AND "rank">30;

Question: What is the Density that has a Population larger than 290,458, and an Area of 91.6?
SQL: SELECT SUM("density") FROM "by_population" WHERE "population">'290,458' AND "area"=91.6;