SELECT X WHERE X使用Y> 1

Question

我可以计算一次使用折扣代码多次的订单吗？

from functools import reduce

所以我希望它重新带回订单：151和161

Order       Codes
123         mowerwo
151         femorfm
151         geirmgr
151         rtert
161         erger
161         wefww
162         wweff

Answer 1

您可以执行以下操作：

SELECT order_num
FROM orderdiscount
GROUP BY discountcode
HAVING COUNT (*) > 1;

如果仅需要代码，则无需进行不必要的计数

Answer 2

您需要将所有列包括在select和group by 列表（此处为order_num）中，这不是诸如 sum之类的聚合函数，计数，平均等

count(*)或count(1)或count(0)或count(order_num)都给出相同的结果。

请使用：

SELECT order_num, count(1) as discount
  FROM ordersdiscount 
 GROUP BY order_num
HAVING count(1)>1;

order_num   discount
   151         3
   161         2

SQL Fiddle Demo