SQL HAVING 实例教程

HAVING
在听取HAVING添加到SQL ，因为在哪里关键字不能使用聚合函数。

有语法的SQL

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

下面我们来看看HAVING  一个例子吧.

_Id
OrderDate
OrderPrice
Customer
1
2008/11/12
1000
Hansen
2
2008/10/23
1600
Nilsen
3
2008/09/02
700
Hansen
4
2008/09/03
300
Hansen
5
2008/08/30
2000
Jensen
6
2008/10/04
100
Nilsen

现在，我们要寻找是否有任何的客户有秩序的总额小于2000年。 

我们使用下面的SQL语句：
 
SELECT Customer,SUM(OrderPrice) FROM Orders
GROUP BY Customer
HAVING SUM(OrderPrice)<2000
 
Customer
SUM(OrderPrice)
Nilsen
1700
现在，我们要寻找的客户，如果“汉森”或“詹森”有秩序的总额超过1500 。 

我们添加一个WHERE子句普通的SQL语句：
 
SELECT Customer,SUM(OrderPrice) FROM Orders
WHERE Customer='Hansen' OR Customer='Jensen'
GROUP BY Customer
HAVING SUM(OrderPrice)>1500
 
结果为.
Customer
SUM(OrderPrice)
Hansen
2000
Jensen
2000