CREATE TABLE flight_fare (flight_id NUMBER, fare_id NUMBER)
CREATE TABLE ground_service (city_code CLOB, airport_code CLOB, transport_type CLOB, ground_fare NUMBER)
CREATE TABLE code_description (code VARCHAR2, description CLOB)
CREATE TABLE equipment_sequence (aircraft_code_sequence VARCHAR2, aircraft_code VARCHAR2)
CREATE TABLE food_service (meal_code CLOB, meal_number NUMBER, compartment CLOB, meal_description VARCHAR2)
CREATE TABLE flight_leg (flight_id NUMBER, leg_number NUMBER, leg_flight NUMBER)
CREATE TABLE month (month_number NUMBER, month_name CLOB)
CREATE TABLE restriction (restriction_code CLOB, advance_purchase NUMBER, stopovers CLOB, saturday_stay_required CLOB, minimum_stay NUMBER, maximum_stay NUMBER, application CLOB, no_discounts CLOB)
CREATE TABLE compartment_class (compartment VARCHAR2, class_type VARCHAR2)
CREATE TABLE flight (aircraft_code_sequence CLOB, airline_code VARCHAR2, airline_flight CLOB, arrival_time NUMBER, connections NUMBER, departure_time NUMBER, dual_carrier CLOB, flight_days CLOB, flight_id NUMBER, flight_number NUMBER, from_airport VARCHAR2, meal_code CLOB, stops NUMBER, time_elapsed NUMBER, to_airport VARCHAR2)
CREATE TABLE airport (airport_code VARCHAR2, airport_name CLOB, airport_location CLOB, state_code VARCHAR2, country_name VARCHAR2, time_zone_code VARCHAR2, minimum_connect_time NUMBER)
CREATE TABLE time_zone (time_zone_code CLOB, time_zone_name CLOB, hours_from_gmt NUMBER)
CREATE TABLE date_day (month_number NUMBER, day_number NUMBER, year NUMBER, day_name VARCHAR2)
CREATE TABLE fare_basis (fare_basis_code CLOB, booking_class CLOB, class_type CLOB, premium CLOB, economy CLOB, discounted CLOB, night CLOB, season CLOB, basis_days CLOB)
CREATE TABLE fare (fare_id NUMBER, from_airport VARCHAR2, to_airport VARCHAR2, fare_basis_code CLOB, fare_airline CLOB, restriction_code CLOB, one_direction_cost NUMBER, round_trip_cost NUMBER, round_trip_required VARCHAR2)
CREATE TABLE city (city_code VARCHAR2, city_name VARCHAR2, state_code VARCHAR2, country_name VARCHAR2, time_zone_code VARCHAR2)
CREATE TABLE aircraft (aircraft_code VARCHAR2, aircraft_description VARCHAR2, manufacturer VARCHAR2, basic_type VARCHAR2, engines NUMBER, propulsion VARCHAR2, wide_body VARCHAR2, wing_span NUMBER, length NUMBER, weight NUMBER, capacity NUMBER, pay_load NUMBER, cruising_speed NUMBER, range_miles NUMBER, pressurized VARCHAR2)
CREATE TABLE dual_carrier (main_airline VARCHAR2, low_flight_number NUMBER, high_flight_number NUMBER, dual_airline VARCHAR2, service_name CLOB)
CREATE TABLE days (days_code VARCHAR2, day_name VARCHAR2)
CREATE TABLE state (state_code CLOB, state_name CLOB, country_name CLOB)
CREATE TABLE class_of_service (booking_class VARCHAR2, rank NUMBER, class_description CLOB)
CREATE TABLE airline (airline_code VARCHAR2, airline_name CLOB, note CLOB)
CREATE TABLE airport_service (city_code VARCHAR2, airport_code VARCHAR2, miles_distant NUMBER, direction VARCHAR2, minutes_distant NUMBER)
CREATE TABLE time_interval (period CLOB, begin_time NUMBER, end_time NUMBER)
CREATE TABLE flight_stop (flight_id NUMBER, stop_number NUMBER, stop_days CLOB, stop_airport CLOB, arrival_time NUMBER, arrival_airline CLOB, arrival_flight_number NUMBER, departure_time NUMBER, departure_airline CLOB, departure_flight_number NUMBER, stop_time NUMBER)

is there one airline that flies from BURBANK to MILWAUKEE milwaukee to ST. LOUIS and from ST. LOUIS to BURBANK
SELECT DISTINCT airline_code FROM airline WHERE ((airline_code IN (SELECT FLIGHTalias1.airline_code FROM flight AS FLIGHTalias1 WHERE (FLIGHTalias1.from_airport IN (SELECT AIRPORT_SERVICEalias2.airport_code FROM airport_service AS AIRPORT_SERVICEalias2 WHERE AIRPORT_SERVICEalias2.city_code IN (SELECT CITYalias2.city_code FROM city AS CITYalias2 WHERE CITYalias2.city_name = 'ST. LOUIS')) AND FLIGHTalias1.to_airport IN (SELECT AIRPORT_SERVICEalias3.airport_code FROM airport_service AS AIRPORT_SERVICEalias3 WHERE AIRPORT_SERVICEalias3.city_code IN (SELECT CITYalias3.city_code FROM city AS CITYalias3 WHERE CITYalias3.city_name = 'BURBANK')))) AND airline_code IN (SELECT FLIGHTalias2.airline_code FROM flight AS FLIGHTalias2 WHERE (FLIGHTalias2.from_airport IN (SELECT AIRPORT_SERVICEalias4.airport_code FROM airport_service AS AIRPORT_SERVICEalias4 WHERE AIRPORT_SERVICEalias4.city_code IN (SELECT CITYalias4.city_code FROM city AS CITYalias4 WHERE CITYalias4.city_name = 'BURBANK')) AND FLIGHTalias2.to_airport IN (SELECT AIRPORT_SERVICEalias5.airport_code FROM airport_service AS AIRPORT_SERVICEalias5 WHERE AIRPORT_SERVICEalias5.city_code IN (SELECT CITYalias5.city_code FROM city AS CITYalias5 WHERE CITYalias5.city_name = 'MILWAUKEE'))))) AND airline_code IN (SELECT FLIGHTalias0.airline_code FROM flight AS FLIGHTalias0 WHERE (FLIGHTalias0.from_airport IN (SELECT AIRPORT_SERVICEalias0.airport_code FROM airport_service AS AIRPORT_SERVICEalias0 WHERE AIRPORT_SERVICEalias0.city_code IN (SELECT CITYalias0.city_code FROM city AS CITYalias0 WHERE CITYalias0.city_name = 'MILWAUKEE')) AND FLIGHTalias0.to_airport IN (SELECT AIRPORT_SERVICEalias1.airport_code FROM airport_service AS AIRPORT_SERVICEalias1 WHERE AIRPORT_SERVICEalias1.city_code IN (SELECT CITYalias1.city_code FROM city AS CITYalias1 WHERE CITYalias1.city_name = 'ST. LOUIS')))))
WITH "_u_10" AS (SELECT "CITYalias0"."city_code" FROM "city" "CITYalias0" WHERE "CITYalias0"."city_name" = 'MILWAUKEE' GROUP BY "city_code"), "_u_11" AS (SELECT "AIRPORT_SERVICEalias0"."airport_code" FROM "airport_service" "AIRPORT_SERVICEalias0" LEFT JOIN "_u_10" "_u_10" ON "AIRPORT_SERVICEalias0"."city_code" = "_u_10"."" WHERE NOT "_u_10"."" IS NULL GROUP BY "airport_code"), "_u_12" AS (SELECT "CITYalias1"."city_code" FROM "city" "CITYalias1" WHERE "CITYalias1"."city_name" = 'ST. LOUIS' GROUP BY "city_code"), "_u_13" AS (SELECT "AIRPORT_SERVICEalias1"."airport_code" FROM "airport_service" "AIRPORT_SERVICEalias1" LEFT JOIN "_u_12" "_u_12" ON "AIRPORT_SERVICEalias1"."city_code" = "_u_12"."" WHERE NOT "_u_12"."" IS NULL GROUP BY "airport_code"), "_u_14" AS (SELECT "FLIGHTalias0"."airline_code" FROM "flight" "FLIGHTalias0" LEFT JOIN "_u_11" "_u_11" ON "FLIGHTalias0"."from_airport" = "_u_11"."" LEFT JOIN "_u_13" "_u_13" ON "FLIGHTalias0"."to_airport" = "_u_13"."" WHERE NOT "_u_11"."" IS NULL AND NOT "_u_13"."" IS NULL GROUP BY "airline_code"), "_u_0" AS (SELECT "CITYalias2"."city_code" FROM "city" "CITYalias2" WHERE "CITYalias2"."city_name" = 'ST. LOUIS' GROUP BY "city_code"), "_u_1" AS (SELECT "AIRPORT_SERVICEalias2"."airport_code" FROM "airport_service" "AIRPORT_SERVICEalias2" LEFT JOIN "_u_0" "_u_0" ON "AIRPORT_SERVICEalias2"."city_code" = "_u_0"."" WHERE NOT "_u_0"."" IS NULL GROUP BY "airport_code"), "_u_2" AS (SELECT "CITYalias3"."city_code" FROM "city" "CITYalias3" WHERE "CITYalias3"."city_name" = 'BURBANK' GROUP BY "city_code"), "_u_3" AS (SELECT "AIRPORT_SERVICEalias3"."airport_code" FROM "airport_service" "AIRPORT_SERVICEalias3" LEFT JOIN "_u_2" "_u_2" ON "AIRPORT_SERVICEalias3"."city_code" = "_u_2"."" WHERE NOT "_u_2"."" IS NULL GROUP BY "airport_code"), "_u_4" AS (SELECT "FLIGHTalias1"."airline_code" FROM "flight" "FLIGHTalias1" LEFT JOIN "_u_1" "_u_1" ON "FLIGHTalias1"."from_airport" = "_u_1"."" LEFT JOIN "_u_3" "_u_3" ON "FLIGHTalias1"."to_airport" = "_u_3"."" WHERE NOT "_u_1"."" IS NULL AND NOT "_u_3"."" IS NULL GROUP BY "airline_code"), "_u_5" AS (SELECT "CITYalias4"."city_code" FROM "city" "CITYalias4" WHERE "CITYalias4"."city_name" = 'BURBANK' GROUP BY "city_code"), "_u_6" AS (SELECT "AIRPORT_SERVICEalias4"."airport_code" FROM "airport_service" "AIRPORT_SERVICEalias4" LEFT JOIN "_u_5" "_u_5" ON "AIRPORT_SERVICEalias4"."city_code" = "_u_5"."" WHERE NOT "_u_5"."" IS NULL GROUP BY "airport_code"), "_u_7" AS (SELECT "CITYalias5"."city_code" FROM "city" "CITYalias5" WHERE "CITYalias5"."city_name" = 'MILWAUKEE' GROUP BY "city_code"), "_u_8" AS (SELECT "AIRPORT_SERVICEalias5"."airport_code" FROM "airport_service" "AIRPORT_SERVICEalias5" LEFT JOIN "_u_7" "_u_7" ON "AIRPORT_SERVICEalias5"."city_code" = "_u_7"."" WHERE NOT "_u_7"."" IS NULL GROUP BY "airport_code"), "_u_9" AS (SELECT "FLIGHTalias2"."airline_code" FROM "flight" "FLIGHTalias2" LEFT JOIN "_u_6" "_u_6" ON "FLIGHTalias2"."from_airport" = "_u_6"."" LEFT JOIN "_u_8" "_u_8" ON "FLIGHTalias2"."to_airport" = "_u_8"."" WHERE NOT "_u_6"."" IS NULL AND NOT "_u_8"."" IS NULL GROUP BY "airline_code") SELECT DISTINCT "airline_code" FROM "airline" LEFT JOIN "_u_14" "_u_14" ON "_u_14"."" = "airline_code" LEFT JOIN "_u_4" "_u_4" ON "_u_4"."" = "airline_code" LEFT JOIN "_u_9" "_u_9" ON "_u_9"."" = "airline_code" WHERE NOT "_u_14"."" IS NULL AND NOT "_u_4"."" IS NULL AND NOT "_u_9"."" IS NULL