CREATE TABLE airlines (alid NUMBER, name CLOB, iata CLOB, icao CLOB, callsign CLOB, country CLOB, active CLOB)
CREATE TABLE airports (apid NUMBER, name CLOB, city CLOB, country CLOB, x NUMBER, y NUMBER, elevation NUMBER, iata CLOB, icao CLOB)
CREATE TABLE routes (rid NUMBER, dst_apid NUMBER, dst_ap CLOB, src_apid NUMBER, src_ap CLOB, alid NUMBER, airline CLOB, codeshare CLOB)

What are the cities with exactly two airports?
SELECT city FROM airports GROUP BY city HAVING COUNT(*) = 2
SELECT "city" FROM "airports" GROUP BY "city" HAVING COUNT(*) = 2