原文:
SQL点滴2—重温sql语句中的join操作
代码
1.join语句
Sql join语句用来合并两个或多个表中的记录。ANSI标准SQL语句中有四种JOIN：INNER，OUTER，LEFTER，RIGHT，一个表或视图也可以可以和它自身做JOIN操作。下面举例说明。下面所举的例子使用的表有Employee和Department，在这两个表中Department.DepartmentID是主键，Employee.DepartmentID是外键。
图1—Employee表
| LastName |
DepartmentID |
Country |
EmployeeID |
| John |
NULL |
Germany |
306 |
| Jones |
33 |
Australia |
124 |
| Rafferty |
31 |
Australia |
123 |
| Robinson |
34 |
United States |
201 |
| Smith |
34 |
Germany |
305 |
图2—Department表
| DepartmentID |
DepartmentName |
| 31 |
Sales |
| 33 |
Engineering |
| 34 |
Clerical |
| 35 |
Marketing |
下面是建表和数据语句：
代码
USE
[
AppressFinancial
]
GO
/* ***** Object: Table [dbo].[department] Script Date: 08/11/2010 15:18:33 ***** */
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [ dbo ] . [ department ] (
[ DepartmentID ] [ int ] NULL ,
[ DepartmentName ] [ varchar ] ( 25 ) NULL ,
UNIQUE NONCLUSTERED
(
[ DepartmentID ] ASC
) WITH (PAD_INDEX = OFF , STATISTICS_NORECOMPUTE = OFF , IGNORE_DUP_KEY = OFF , ALLOW_ROW_LOCKS = ON , ALLOW_PAGE_LOCKS = ON ) ON [ PRIMARY ]
) ON [ PRIMARY ]
GO
SET ANSI_PADDING OFF
GO
GO
/* ***** Object: Table [dbo].[department] Script Date: 08/11/2010 15:18:33 ***** */
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [ dbo ] . [ department ] (
[ DepartmentID ] [ int ] NULL ,
[ DepartmentName ] [ varchar ] ( 25 ) NULL ,
UNIQUE NONCLUSTERED
(
[ DepartmentID ] ASC
) WITH (PAD_INDEX = OFF , STATISTICS_NORECOMPUTE = OFF , IGNORE_DUP_KEY = OFF , ALLOW_ROW_LOCKS = ON , ALLOW_PAGE_LOCKS = ON ) ON [ PRIMARY ]
) ON [ PRIMARY ]
GO
SET ANSI_PADDING OFF
GO
