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SQL HAVING 子句


SQL HAVING 子句

使用 HAVING子句是因为WHERE关键字不能与聚合函数一起使用。

HAVING 语法

SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
HAVING condition
ORDER BY column_name(s);

演示数据库

以下是Northwind示例数据库中“Customers”表的选择:

CustomerID CustomerName ContactName Address City PostalCode Country
1 Alfreds Futterkiste Maria Anders Obere Str. 57 Berlin 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constituciуn 2222 Mйxico D.F. 05021 Mexico
3 Antonio Moreno Taquerнa Antonio Moreno Mataderos 2312 Mйxico D.F. 05023 Mexico
4 Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbkцp Christina Berglund Berguvsvдgen 8 Luleе S-958 22 Sweden

SQL HAVING 实例

以下SQL语句列出了每个国家的客户数。仅包括拥有超过5个客户的国家:

实例

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
HAVING COUNT(CustomerID) > 5;

运行实例»

以下SQL语句列出了每个国家的客户数量,从高到低排序(仅包括客户数超过5的国家):

实例

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
HAVING COUNT(CustomerID) > 5
ORDER BY COUNT(CustomerID) DESC;

运行实例»


演示数据库

以下是Northwind示例数据库中“Orders”表的选择:

OrderID CustomerID EmployeeID OrderDate ShipperID
10248 90 5 1996-07-04 3
10249 81 6 1996-07-05 1
10250 34 4 1996-07-08 2

并从“Employees”表中选择:

EmployeeID LastName FirstName BirthDate Photo Notes
1 Davolio Nancy 1968-12-08 EmpID1.pic Education includes a BA....
2 Fuller Andrew 1952-02-19 EmpID2.pic Andrew received his BTS....
3 Leverling Janet 1963-08-30 EmpID3.pic Janet has a BS degree....

更多实例

以下SQL语句列出已注册10个以上订单的员工:

实例

SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders
FROM (Orders
INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID)
GROUP BY LastName
HAVING COUNT(Orders.OrderID) > 10;

运行实例»

以下SQL语句列出了员工“Davolio”或“Fuller”是否已注册超过25个订单:

实例

SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders
FROM Orders
INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID
WHERE LastName = 'Davolio' OR LastName = 'Fuller'
GROUP BY LastName
HAVING COUNT(Orders.OrderID) > 25;

运行实例»