Задача 10

WITH cte AS (
    SELECT
        DATE_TRUNC('year', paid_at)::date AS year,
        SUM(total_amt) AS sum
    FROM
        tools_shop.orders
    GROUP BY
        year
)
SELECT
    year,
    sum,
    LEAD(sum, 1, sum) OVER (ORDER BY year) - sum AS dif
FROM
    cte