mysql - 按计数分组可能吗？

Question

我有 2 个表:

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

我想知道这个:

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

我有这个:

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

Answer 1

这给出了每个客户的订单量

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

现在将其用作表，并对其进行查询

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