每个顾客在餐厅消费的总金额是多少？ 无法看到不同的 customer_id .. 仅显示所有金额的一个相同 id

Question

Query

select customer_id ,(numbers*price) as amount 
from (select *,  count(s.product_id) as numbers
      from sales s group by product_id) as sub1 
inner join
( select s.product_id, price 
  from menu m inner join sales s on m.product_id = s.product_id 
  group by product_id) as sub2 on sub1.product_id = sub2.product_id; 

sample data:

INSERT INTO sales ("customer_id", "order_date", "product_id") 
VALUES ('A', '2021-01-01', '1'),('A', '2021-01-01', '2'),('A', '2021-01-07', '2'),('A', '2021-01-10', '3'),('A', '2021-01-11', '3'),('A', '2021-01-11', '3'),('B', '2021-01-01', '2'),('B', '2021-01-02', '2'),('B', '2021-01-04', '1'),('B', '2021-01-11', '1'),('B', '2021-01-16', '3'),('B', '2021-02-01', '3'),('C', '2021-01-01', '3'),('C', '2021-01-01', '3'),('C', '2021-01-07', '3'); 

INSERT INTO menu ("product_id", "product_name", "price") 
VALUES ('1', 'sushi', '10'),('2', 'curry', '15'),('3', 'ramen', '12'); 

Output

customer_id   amount
A              30
A              60
A              96

whereas i want it to show A,B,C as customer ids as the amount is calculated correctly for them. Its showing A as customer_id for all three as first three ids in sales table are for customer A. I tried group by with customer id as well.. it shows only one result, ie A and 30.

Answer 1

seems like you want sales report per product:

select  product_name, sum(price) amount
from sales s
join menu m on s.product_id = m.product_id
group by product_name
order by sum(price)

product_name	amount
sushi	30
curry	60
ramen	96

but if you want total sale per customer:

select  customer_id , sum(price) amount
from sales s
join menu m on s.product_id = m.product_id
group by customer_id
order by customer_id

customer_id	amount
A	76
B	74
C	36

db<>fiddle here