满足特定条件时在MySQL中求和

Question

当订单项匹配（在MySql中）时，我想对下表的价格求和。 表1-

Customers.  OrderItem. Price
Customer A.  Pizza.         300
 Customer B.   Pizza.       500
 Customer A.    Pizza.      200
  Customer B.    Pizza.      300
  Customer A.     Softdrink.  50
   Customer A.    Softdrink.    20
   Customer B.     Softdrink.    30
   Customer B.     Softdrink.    60

要获得像这样的新表：-

     Customer.    Pizza.   Softdrink
       Customer A. 500.     70
        Customer B. 800.     90

在MySql中。

Answer 1

您可以使用条件聚合：

SELECT
    Customer,
    SUM(CASE WHEN OrderItem = 'Pizza'     THEN Price ELSE 0 END) AS Pizza,
    SUM(CASE WHEN OrderItem = 'Softdrink' THEN Price ELSE 0 END) AS Softdrink
FROM yourTable
GROUP BY
    Customer;

Demo