How many units of item no.5 were sold in store no.3 on the day the temperature range was the biggest?
item no. 5 refers to item_nbr = 5; store no.3 refers to store_nbr = 3; when the temperature range was the biggest refers to Max(Subtract(tmax, tmin))
SELECT t2.units FROM relation AS T1 INNER JOIN sales_in_weather AS T2 ON T1.store_nbr = T2.store_nbr INNER JOIN weather AS T3 ON T1.station_nbr = T3.station_nbr WHERE T2.store_nbr = 3 AND T2.item_nbr = 5 ORDER BY t3.tmax - t3.tmin DESC LIMIT 1
CREATE TABLE sales_in_weather
(
    date      DATE,
    store_nbr INTEGER,
    item_nbr  INTEGER,
    units     INTEGER,
    primary key (store_nbr, date, item_nbr)
);
CREATE TABLE weather
(
    station_nbr INTEGER,
    date        DATE,
    tmax        INTEGER,
    tmin        INTEGER,
    tavg        INTEGER,
    depart      INTEGER,
    dewpoint    INTEGER,
    wetbulb     INTEGER,
    heat        INTEGER,
    cool        INTEGER,
    sunrise     TEXT,
    sunset      TEXT,
    codesum     TEXT,
    snowfall    REAL,
    preciptotal REAL,
    stnpressure REAL,
    sealevel    REAL,
    resultspeed REAL,
    resultdir   INTEGER,
    avgspeed    REAL,
    primary key (station_nbr, date)
);
CREATE TABLE relation
(
    store_nbr   INTEGER
            primary key,
    station_nbr INTEGER,
    foreign key (store_nbr) references sales_in_weather(store_nbr),
    foreign key (station_nbr) references weather(station_nbr)
);
