CREATE TABLE county_public_safety (county_id NUMBER, name CLOB, population NUMBER, police_officers NUMBER, residents_per_officer NUMBER, case_burden NUMBER, crime_rate NUMBER, police_force CLOB, location CLOB)
CREATE TABLE city (city_id NUMBER, county_id NUMBER, name CLOB, white NUMBER, black NUMBER, amerindian NUMBER, asian NUMBER, multiracial NUMBER, hispanic NUMBER)

How many cities are in counties that have populations of over 20000?
SELECT COUNT(*) FROM city WHERE county_id IN (SELECT county_id FROM county_public_safety WHERE population > 20000)
SELECT COUNT(*) FROM "city" WHERE "county_id" IN (SELECT "county_id" FROM "county_public_safety" WHERE "population" > 20000)