SELECT * FROM example_db (
SELECT
model,
year,
price,
transmission,
mileage,
fueltype,
mpg, -- miles per galon
ROUND(CAST((mpg / 2.3521458) AS numeric), 1) AS kml, -- kilometers per liter
(date_part('year', CURRENT_DATE)-year) AS years_old, -- age of a car
COUNT(*) OVER (PARTITION BY model, year) AS units_to_sell, -- how many units of a certain model are sold in a year
ROUND((CAST(tax AS decimal) / price), 3) AS tax_div_price -- value of tax divided by price of a car
FROM demo_data.used_car_price
);