SQL RIGHT JOIN 關鍵字

RIGHT JOIN 關鍵字從右表(table2)返回所有的行,即使左表(table1)中沒有匹配。如果左表中沒有匹配,則結果為 NULL。

SQL RIGHT JOIN 語法

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

或:

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

注釋:在某些數據庫中,RIGHT JOIN 稱為 RIGHT OUTER JOIN。

SQL RIGHT JOIN



演示數據庫

在本教程中,我們將使用眾所周知的 Northwind 樣本數據庫。

下面是選自 "Orders" 表的數據:

OrderID CustomerID EmployeeID OrderDate ShipperID
10308 2 7 1996-09-18 3
10309 37 3 1996-09-19 1
10310 77 8 1996-09-20 2

選自 "Employees" 表的數據:

EmployeeID LastName FirstName BirthDate Photo Notes
1 Davolio Nancy 12/8/1968 EmpID1.pic Education includes a BA in psychology.....
2 Fuller Andrew 2/19/1952 EmpID2.pic Andrew received his BTS commercial and....
3 Leverling Janet 8/30/1963 EmpID3.pic Janet has a BS degree in chemistry....


SQL RIGHT JOIN 實例

下面的 SQL 語句將返回所有員工及他們處理的訂單:

實例

SELECT Orders.OrderID, Employees.FirstName
FROM Orders
RIGHT JOIN Employees
ON Orders.EmployeeID=Employees.EmployeeID
ORDER BY Orders.OrderID;

注釋:RIGHT JOIN 關鍵字從右表(Employees)返回所有的行,即使左表(Orders)中沒有匹配。