SQL RIGHT JOIN 关键字与SQL LEFT JOIN 关键字非常相似,它会选择所有在右表中匹配的记录,而不管在左表中是否有匹配。
SQL RIGHT JOIN 语法
SELECT Table1.Column1, Table1.Column2, ... , Table2.Column1, Table2.Column2, ... FROM Table1 RIGHT JOIN Table2 ON Table1.ColumnName = Table2.ColumnName
SQL RIGHT JOIN 范例
数据表: Employees
EmployeeId | FirstName | LastName | Department | Salary |
---|---|---|---|---|
203 | Ahooc | Yuish | Finance | 78000 |
204 | Quisheen | Nnuchen | Finance | 45800 |
205 | Lshhwe | Aceed | Finance | 57000 |
数据表: Tickets
TicketID | TicketNo | EmployeeId |
---|---|---|
1 | 2200 | 203 |
2 | 2338 | 204 |
3 | 2369 | 205 |
4 | 2410 | 206 |
选择所有的Tickets,如果它属于某个职员(Employee),列出该职员(Employee):
SELECT Employees.EmployeeId , Employees.FirstName , Employees.LastName , Tickets.TicketNo FROM Employees RIGHT JOIN Tickets ON Employees.EmployeeId = Tickets.EmployeeId
结果会类似于:
EmployeeId | FirstName | LastName | TicketNo |
---|---|---|---|
203 | Ahooc | Yuish | 2200 |
204 | Quisheen | Nnuchen | 2338 |
205 | Lshhwe | Aceed | 2369 |
2410 |
注:Ticket 2410不属于任何任何Employee,但它还是出现在结果集中,其中Employee信息为null。