Pandas nunique to COUNT DISTINCT

How many different customers ordered? COUNT(DISTINCT customer_id).

SELECT COUNT(DISTINCT customer_id) FROM Orders;
SELECT status, COUNT(DISTINCT customer_id) AS customers
FROM Orders
GROUP BY status;

COUNT(DISTINCT) ignores NULL. pandas nunique drops NA by default too.

Canonical translation

SELECT COUNT(DISTINCT customer_id) FROM Orders;
SELECT status, COUNT(DISTINCT customer_id) AS customers
FROM Orders
GROUP BY status;