如何在SQL中作为单独的列返回resultset中的最小值？

我一直在努力解决以下SQL查询

我的结果集现在是：

| Id | Customer | Sales |
| 1  | 1        | 10    |
| 2  | 1        | 20    |
| 3  | 2        | 30    |
| 4  | 2        | 40    |

我想做的是增加一个列，显示该客户的最小销售额：

| Id | Customer | Sales | SmallestSale |
| 1  | 1        | 10    | 10           |
| 2  | 1        | 20    | 10           |
| 3  | 2        | 30    | 30           |
| 4  | 2        | 40    | 30           |

由于获取这三列的select查询现在相当复杂，我希望避免子查询

有什么想法吗

---

Mika

假设您的RDBMS支持窗口聚合

SELECT  Id, 
        Customer,
        Sales, 
        MIN(Sales) OVER (PARTITION BY Customer) AS SmallestSale 
FROM YourTable

select s.Id, s.Customer, s.Sales, sm.SmallestSale 
from Sales s
inner join (
    select Customer, min(sales) as SmallestSale 
    from Sales
    group by Customer
) sm on s.Customer = sm.Customer