SQL点滴2—重温sql语句中的join操作
2014-12-03 16:31
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原文:SQL点滴2—重温sql语句中的join操作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
图2—Department表
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
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 |
DepartmentID | DepartmentName |
31 | Sales |
33 | Engineering |
34 | Clerical |
35 | Marketing |
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
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