SQL RIGHT JOIN

SQL RIGHT JOIN 说明

关键字 RIGHT JOIN 返回右表 (table2) 中的所有记录以及左表 (table1) 中的相应记录。

如果没有匹配，结果将为左侧 0 条记录。

RIGHT JOIN 语法

SELECT column_name(s)
FROM table1
RIGHT JOIN table2
ON table1.column_name = table2.column_name

在某些数据库中，RIGHT JOIN 称为 RIGHT OUTER JOIN。

SQL INNER JOIN

演示数据库

在本教程中，我们将使用著名的示例数据库“Northwind”。

以下是表“Orders”（“订单”）中的示例：

ProductID	OrderID	CustomerID	EmployeeID	OrderDate	ShipperID
1	10248	90	5	1996-07-04	3
2	10249	81	6	1996-07-05	1
3	10250	34	4	1996-07-08	2
4	10251	84	3	1996-07-08	1
5	10252	76	4	1996-07-09	2

并从表“Employees”（“员工”）中进行选择：

EmployeeID	LastName	FirstName	BirthDate	Photo	Notes
1	Davolio	Nancy	12/8/1968	EmpID1.pic	Education includes a BA in psychology from Colorado State University. She also completed (The Art of the Cold Call). Nancy is a member of 'Toastmasters International'.
2	Fuller	Andrew	2/19/1952	EmpID2.pic	Andrew received his BTS commercial and a Ph.D. in international marketing from the University of Dallas. He is fluent in French and Italian and reads German. He joined the company as a sales representative, was promoted to sales manager and was then named vice president of sales. Andrew is a member of the Sales Management Roundtable, the Seattle Chamber of Commerce, and the Pacific Rim Importers Association.
3	Leverling	Janet	8/30/1963	EmpID3.pic	Janet has a BS degree in chemistry from Boston College). She has also completed a certificate program in food retailing management. Janet was hired as a sales associate and was promoted to sales representative.
4	Peacock	Margaret	9/19/1958	EmpID4.pic	Margaret holds a BA in English literature from Concordia College and an MA from the American Institute of Culinary Arts. She was temporarily assigned to the London office before returning to her permanent post in Seattle.
5	Buchanan	Steven	3/4/1955	EmpID5.pic	Steven Buchanan graduated from St. Andrews University, Scotland, with a BSC degree. Upon joining the company as a sales representative, he spent 6 months in an orientation program at the Seattle office and then returned to his permanent post in London, where he was promoted to sales manager. Mr. Buchanan has completed the courses 'Successful Telemarketing' and 'International Sales Management'. He is fluent in French.

SQL RIGHT JOIN 示例

以下 SQL 语句将返回所有员工以及他们可能下的任何订单：

Run SQLSELECT Orders.OrderID, Employees.LastName, Employees.FirstName 
FROM Orders 
RIGHT JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID 
ORDER BY Orders.OrderID

RIGHT JOIN 关键字返回右表 (Employees) 中的所有记录，即使左表 (Orders) 中没有匹配项。