What is the percentage of flights which landed at Pittsburgh were faster than scheduled?
percentage = MULTIPLY(DIVIDE(SUM(ACTUAL_ELAPSED_TIME < T2.CRS_ELAPSED_TIME), COUNT(Code)), 100); landed at refers to DEST; Pittsburgh refers to Description which contains 'Pittsburgh'; faster than scheduled refers to ACTUAL_ELAPSED_TIME < CRS_ELAPSED_TIME;
SELECT CAST(SUM(CASE WHEN T1.ACTUAL_ELAPSED_TIME < T1.CRS_ELAPSED_TIME THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(*) FROM Airlines AS T1 INNER JOIN Airports AS T2 ON T2.Code = T1.DEST WHERE T2.Description LIKE '%Pittsburgh%' AND T1.CRS_ELAPSED_TIME IS NOT NULL AND T1.ACTUAL_ELAPSED_TIME IS NOT NULL
CREATE TABLE IF NOT EXISTS "Air Carriers"
(
    Code        INTEGER
            primary key,
    Description TEXT
);
CREATE TABLE Airports
(
    Code        TEXT
            primary key,
    Description TEXT
);
CREATE TABLE Airlines
(
    FL_DATE               TEXT,
    OP_CARRIER_AIRLINE_ID INTEGER,
    TAIL_NUM              TEXT,
    OP_CARRIER_FL_NUM     INTEGER,
    ORIGIN_AIRPORT_ID     INTEGER,
    ORIGIN_AIRPORT_SEQ_ID INTEGER,
    ORIGIN_CITY_MARKET_ID INTEGER,
    ORIGIN                TEXT,
    DEST_AIRPORT_ID       INTEGER,
    DEST_AIRPORT_SEQ_ID   INTEGER,
    DEST_CITY_MARKET_ID   INTEGER,
    DEST                  TEXT,
    CRS_DEP_TIME          INTEGER,
    DEP_TIME              INTEGER,
    DEP_DELAY             INTEGER,
    DEP_DELAY_NEW         INTEGER,
    ARR_TIME              INTEGER,
    ARR_DELAY             INTEGER,
    ARR_DELAY_NEW         INTEGER,
    CANCELLED             INTEGER,
    CANCELLATION_CODE     TEXT,
    CRS_ELAPSED_TIME      INTEGER,
    ACTUAL_ELAPSED_TIME   INTEGER,
    CARRIER_DELAY         INTEGER,
    WEATHER_DELAY         INTEGER,
    NAS_DELAY             INTEGER,
    SECURITY_DELAY        INTEGER,
    LATE_AIRCRAFT_DELAY   INTEGER,
    FOREIGN KEY (ORIGIN) REFERENCES Airports(Code),
    FOREIGN KEY (DEST) REFERENCES Airports(Code),
    FOREIGN KEY (OP_CARRIER_AIRLINE_ID) REFERENCES "Air Carriers"(Code)
);
