如何使用組，內部連接和總和？

Question

我有兩個表：產品 & 銷售。

產品

id- productname - grp 

11 bmwblue  bmw 
12 bmwwhite  bmw 
13 audiblack  audi 
14 audiwhite  audi 

銷售

id productid amount 

1  11  2 
2  12  1 
x  13  5 
x  14  3 

我怎樣才能顯示;

audi 8，bmw 3？

Answer 1

SELECT grp, 
     sum(amount) AS total_grp_amount 
FROM products AS p 
JOIN sales AS s ON p.id = s.product_id 
GROUP BY grp 

我想你正在尋找這個。