SQL中HAVING 子句

HAVING 子句

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。

SQL HAVING 语法

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

SQL HAVING 实例

我们拥有下面这个 "Orders" 表：

O_IdOrderDateOrderPriceCustomer12008/12/291000Bush22008/11/231600Carter32008/10/05700Bush42008/09/28300Bush52008/08/062000Adams62008/07/21100Carter

现在，我们希望查找订单总金额少于 2000 的客户。

我们使用如下 SQL 语句：

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

结果集类似：

CustomerSUM(OrderPrice)Carter1700

现在我们希望查找客户 "Bush" 或 "Adams" 拥有超过 1500 的订单总金额。

我们在 SQL 语句中增加了一个普通的 WHERE 子句：

SELECT Customer,SUM(OrderPrice) FROM Orders WHERE Customer='Bush' OR Customer='Adams' GROUP BY Customer HAVING SUM(OrderPrice)>1500

结果集：

CustomerSUM(OrderPrice)Bush2000Adams2000