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mysql 语法

常用函数

group by

order by

case when

https://blog.csdn.net/y_bccl27/article/details/113941219

having

  • 在 SQL 中增加 HAVING 子句原因是，WHERE 关键字无法与合计函数一起使用。
SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE column_name operator value
GROUP BY column_name
HAVING aggregate_function(column_name) operator value
| O_Id | OrderDate  | OrderPrice | Customer |
| :--- | :--------- | :--------- | :------- |
| 1    | 2008/12/29 | 1000       | Bush     |
| 2    | 2008/11/23 | 1600       | Carter   |
| 3    | 2008/10/05 | 700        | Bush     |
| 4    | 2008/09/28 | 300        | Bush     |
| 5    | 2008/08/06 | 2000       | Adams    |
| 6    | 2008/07/21 | 100        | Carter   |

现在，我们希望查找订单总金额少于 2000 的客户。
使用如下：

SELECT Customer,SUM(OrderPrice) FROM Orders
GROUP BY Customer
HAVING SUM(OrderPrice)<2000