Group by count possible?

Question

i have 2 tables:

1.customer (contains customers)
2.customer_order (contains orders)

I want to know this:

no. of customers with 0 orders
no. of customers with 1 order
no. of customers with 2 orders
etc

i have this:

SELECT COUNT(co.id)
FROM customer c
LEFT JOIN customer_order co
ON c.id=co.id_customer
GROUP BY ??? ;

Answer 1

This gives the amount of orders per customer

SELECT co.id Customer, COUNT(*) Orders
FROM customer_order co  
GROUP BY co.id_customer;

Now use that as a table, and query it

SELECT Orders, COUNT(*)
FROM (
  SELECT co.id Customer, COUNT(*) Orders
  FROM customer_order co  
  GROUP BY co.id_customer;
)
GROUP BY Orders