Which country produced the car with the lowest mileage per gallon?
the lowest mileage per gallon refers to min(mpg)
SELECT T3.country FROM data AS T1 INNER JOIN production AS T2 ON T1.ID = T2.ID INNER JOIN country AS T3 ON T3.origin = T2.country ORDER BY T1.mpg ASC LIMIT 1
CREATE TABLE country
(
    origin  INTEGER
            primary key,
    country TEXT
);
CREATE TABLE price
(
    ID    INTEGER
            primary key,
    price REAL
);
CREATE TABLE data
(
    ID           INTEGER
            primary key,
    mpg          REAL,
    cylinders    INTEGER,
    displacement REAL,
    horsepower   INTEGER,
    weight       INTEGER,
    acceleration REAL,
    model        INTEGER,
    car_name     TEXT,
    foreign key (ID) references price(ID)
);
CREATE TABLE production
(
    ID         INTEGER,
    model_year INTEGER,
    country    INTEGER,
    primary key (ID, model_year),
    foreign key (country) references country(origin),
    foreign key (ID) references data(ID),
    foreign key (ID) references price(ID)
);
