MySQL乘法

Question

我正在尝试在 MySQL 中进行乘法运算。我有下表称为 vehicul:

id car_type car_model  number price  car_id
1    audi    <model1>    2     320     1
2    audi    <model2>    4     100     1
3    bmw     <model1>    3     240     2
4    bmw     <model2>    6     500     2
5    bmw     <model3>    1     400     2

我有这个命令:

SELECT car_type, sum(price) FROM vehicul as v, GROUP BY marca

显示以下内容:

car_type  price 
audi       420  
bmw        1140

但我想要的是显示数字*价格，结果是:

car_type  price 
audi       1040  
bmw        4120

基本上.. sum(number*price).. 我该怎么做？我试过这样做:

SELECT car_type, sum(price*number) FROM vehicul as v, GROUP BY marca

但我得到:

#1052 - Column 'number' in field list is ambiguous 

Answer 1

选择car_type，sum(price*number) 作为price from vehicul group by car_type..

http://sqlfiddle.com/#!2/3d881/1

你应该使用 sum(field_1*field_2) 而不是 sum()*sum()