CREATE TABLE trip (zip_code VARCHAR, mean_humidity INT)
CREATE TABLE weather (zip_code VARCHAR, mean_humidity INT)

Give me the zip code where the average mean humidity is below 70 and at least 100 trips took place.
SELECT zip_code FROM weather GROUP BY zip_code HAVING AVG(mean_humidity) < 70 INTERSECT SELECT zip_code FROM trip GROUP BY zip_code HAVING COUNT(*) >= 100
SELECT "zip_code" FROM "weather" GROUP BY "zip_code" HAVING AVG("mean_humidity") < 70 INTERSECT SELECT "zip_code" FROM "trip" GROUP BY "zip_code" HAVING COUNT(*) >= 100