Функция ранжирования NTILE()

SELECT count(distinct order_id)

FROM
(SELECT order_id,
       total_amt,
       NTILE(10) OVER (ORDER BY total_amt) AS dd
FROM tools_shop.orders) AS kk
GROUP BY dd;

/*основной вариант*/
SELECT order_id,
       total_amt,
       NTILE(10) OVER (ORDER BY total_amt)
FROM tools_shop.orders;