SQL HAVING 子句
HAVING 子句
在 SQL 中增加 HAVING 子句原因是，WHERE 關鍵字無法與合計函數(shù)一起使用。
SQL HAVING 語法
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 實例
我們擁有下面這個 "Orders" 表：
| 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 |
現(xiàn)在，我們希望查找訂單總金額少于 2000 的客戶。
我們使用如下 SQL 語句：
SELECT Customer,SUM(OrderPrice) FROM Orders GROUP BY Customer HAVING SUM(OrderPrice)<2000
結(jié)果集類似：
| Customer | SUM(OrderPrice) |
|---|---|
| Carter | 1700 |
現(xiàn)在我們希望查找客戶 "Bush" 或 "Adams" 擁有超過 1500 的訂單總金額。
我們在 SQL 語句中增加了一個普通的 WHERE 子句：
SELECT Customer,SUM(OrderPrice) FROM Orders WHERE Customer='Bush' OR Customer='Adams' GROUP BY Customer HAVING SUM(OrderPrice)>1500
結(jié)果集：
| Customer | SUM(OrderPrice) |
|---|---|
| Bush | 2000 |
| Adams | 2000 |