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18.03.2009, 11:33
#35876080
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Я бы оттолкнулся от предметной области и идей объектно-ориентированного проектирования. То или иное решение зависит от задач, решаемых Вашим приложением. Скажем, если существует объект Инструмент и два его наследника ЦеннаяБумага : Инструмент и Фьючерс : Инструмент, то почему бы не реализовать маппинг этих объектов на реляционные таблицы типа Table-per-hierarchy inheritance или Table-per-type inheritance (в зависимости от того, что Вам лучше подходит). Ниже процитирую скрипт, создающий базу с иллюстрацией обоих подходов. Скопировано отсюда .
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USE [master]
GO
CREATE DATABASE [SchoolData]
GO
USE [SchoolData]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[DeptBusiness]')
AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[DeptBusiness](
[BusinessDeptID] [int] NOT NULL,
[LegalBudget] [money] NOT NULL,
[AccountingBudget] [money] NOT NULL,
CONSTRAINT [PK_DeptBusiness] PRIMARY KEY CLUSTERED
(
[BusinessDeptID] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[DeptEngineering]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[DeptEngineering](
[EngineeringDeptID] [int] NOT NULL,
[FiberOpticsBudget] [money] NOT NULL,
[LabBudget] [money] NOT NULL,
CONSTRAINT [PK_DeptEngineering] PRIMARY KEY CLUSTERED
(
[EngineeringDeptID] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[DeptMusic]')
AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[DeptMusic](
[DeptMusicID] [int] NOT NULL,
[TheaterBudget] [money] NOT NULL,
[InstrumentBudget] [money] NOT NULL,
CONSTRAINT [PK_DeptMusic] PRIMARY KEY CLUSTERED
(
[DeptMusicID] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Course]')
AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[Course](
[CourseID] [int] NOT NULL,
[Title] [nvarchar]( 100 ) NOT NULL,
[StartDate] [datetime] NOT NULL,
[EndDate] [datetime] NOT NULL,
[Credits] [int] NULL,
CONSTRAINT [PK_Course] PRIMARY KEY CLUSTERED
(
[CourseID] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Person]')
AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[Person](
[PersonID] [int] NOT NULL,
[FirstName] [nvarchar]( 50 ) NOT NULL,
[LastName] [nvarchar]( 50 ) NOT NULL,
[HireDate] [datetime] NULL,
[EnrollmentDate] [datetime] NULL,
[PersonCategory] [smallint] NOT NULL,
[AdminDate] [datetime] NULL,
CONSTRAINT [PK_Person] PRIMARY KEY CLUSTERED
(
[PersonID] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Enrollment]')
AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[Enrollment](
[EnrollmentID] [int] NOT NULL,
[CourseID] [int] NOT NULL,
[StudentID] [int] NOT NULL,
CONSTRAINT [PK_Enrollment] PRIMARY KEY CLUSTERED
(
[EnrollmentID] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[CourseInstructor]')
AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[CourseInstructor](
[CourseInstructorID] [int] NOT NULL,
[CourseID] [int] NOT NULL,
[InstructorID] [int] NOT NULL,
CONSTRAINT [PK_CourseInstructor] PRIMARY KEY CLUSTERED
(
[CourseInstructorID] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Department]')
AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[Department](
[DepartmentID] [int] NOT NULL,
[Name] [nvarchar]( 50 ) NOT NULL,
[Budget] [money] NOT NULL,
[StartDate] [datetime] NOT NULL,
[Administrator] [int] NULL,
CONSTRAINT [PK_Department] PRIMARY KEY CLUSTERED
(
[DepartmentID] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
IF NOT EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'[dbo].[FK_Enrollment_Course]')
AND parent_object_id = OBJECT_ID(N'[dbo].[Enrollment]'))
ALTER TABLE [dbo].[Enrollment] WITH CHECK ADD CONSTRAINT [FK_Enrollment_Course] FOREIGN KEY([CourseID])
REFERENCES [dbo].[Course] ([CourseID])
GO
ALTER TABLE [dbo].[Enrollment] CHECK CONSTRAINT [FK_Enrollment_Course]
GO
IF NOT EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'[dbo].[FK_Enrollment_Student]')
AND parent_object_id = OBJECT_ID(N'[dbo].[Enrollment]'))
ALTER TABLE [dbo].[Enrollment] WITH CHECK ADD CONSTRAINT [FK_Enrollment_Student] FOREIGN KEY([StudentID])
REFERENCES [dbo].[Person] ([PersonID])
GO
ALTER TABLE [dbo].[Enrollment] CHECK CONSTRAINT [FK_Enrollment_Student]
GO
IF NOT EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'[dbo].[FK_CourseInstructor_Course]')
AND parent_object_id = OBJECT_ID(N'[dbo].[CourseInstructor]'))
ALTER TABLE [dbo].[CourseInstructor] WITH CHECK ADD CONSTRAINT [FK_CourseInstructor_Course] FOREIGN KEY([CourseID])
REFERENCES [dbo].[Course] ([CourseID])
GO
ALTER TABLE [dbo].[CourseInstructor] CHECK CONSTRAINT [FK_CourseInstructor_Course]
GO
IF NOT EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'[dbo].[FK_CourseInstructor_Instructor]')
AND parent_object_id = OBJECT_ID(N'[dbo].[CourseInstructor]'))
ALTER TABLE [dbo].[CourseInstructor] WITH CHECK ADD CONSTRAINT [FK_CourseInstructor_Instructor] FOREIGN KEY([InstructorID])
REFERENCES [dbo].[Person] ([PersonID])
GO
ALTER TABLE [dbo].[CourseInstructor] CHECK CONSTRAINT [FK_CourseInstructor_Instructor]
GO
IF NOT EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'[dbo].[FK_Department_Administrator]')
AND parent_object_id = OBJECT_ID(N'[dbo].[Department]'))
ALTER TABLE [dbo].[Department] WITH CHECK ADD CONSTRAINT [FK_Department_Administrator] FOREIGN KEY([Administrator])
REFERENCES [dbo].[Person] ([PersonID])
GO
ALTER TABLE [dbo].[Department] CHECK CONSTRAINT [FK_Department_Administrator]
Надеюсь, в чем-то поможет... |
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