вроде чуток разобрался,но всеравно есть вопросы.вот например часть из рез-ов того примера:
| Код |
SET ANSI_NULLS ON
SET QUOTED_IDENTIFIER ON
CREATE TABLE [dbo].[Employees](
[EmployeeID] [int] IDENTITY(1,1) NOT NULL,
[LastName] [nvarchar](20) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
[FirstName] [nvarchar](10) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
[Title] [nvarchar](30) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[TitleOfCourtesy] [nvarchar](25) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[BirthDate] [datetime] NULL,
[HireDate] [datetime] NULL,
[Address] [nvarchar](60) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[City] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Region] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[PostalCode] [nvarchar](10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Country] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[HomePhone] [nvarchar](24) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Extension] [nvarchar](4) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Photo] [image] NULL,
[Notes] [ntext] COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[ReportsTo] [int] NULL,
[PhotoPath] [nvarchar](255) COLLATE SQL_Latin1_General_CP1_CI_AS NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
SET ANSI_NULLS ON
SET QUOTED_IDENTIFIER ON
CREATE TABLE [dbo].[Customers](
[CustomerID] [nchar](5) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
[CompanyName] [nvarchar](40) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
[ContactName] [nvarchar](30) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[ContactTitle] [nvarchar](30) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Address] [nvarchar](60) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[City] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Region] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[PostalCode] [nvarchar](10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Country] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Phone] [nvarchar](24) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Fax] [nvarchar](24) COLLATE SQL_Latin1_General_CP1_CI_AS NULL
) ON [PRIMARY]
SET ANSI_NULLS ON
SET QUOTED_IDENTIFIER ON
CREATE TABLE [dbo].[Shippers](
[ShipperID] [int] IDENTITY(1,1) NOT NULL,
[CompanyName] [nvarchar](40) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
[Phone] [nvarchar](24) COLLATE SQL_Latin1_General_CP1_CI_AS NULL
) ON [PRIMARY]
SET ANSI_NULLS ON
SET QUOTED_IDENTIFIER ON
CREATE TABLE [dbo].[Orders](
[OrderID] [int] IDENTITY(1,1) NOT NULL,
[CustomerID] [nchar](5) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[EmployeeID] [int] NULL,
[OrderDate] [datetime] NULL,
[RequiredDate] [datetime] NULL,
[ShippedDate] [datetime] NULL,
[ShipVia] [int] NULL,
[Freight] [money] NULL,
[ShipName] [nvarchar](40) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[ShipAddress] [nvarchar](60) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[ShipCity] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[ShipRegion] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[ShipPostalCode] [nvarchar](10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[ShipCountry] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL
) ON [PRIMARY]
|
после проверки выяснилось,что здесь нижняя таблица зависит от всех перечисленных выше.но как узнать по каким полям?
там где есть IDENTITY(1,1) почти понятно.но почему в Employees IDENTITY есть, а в Customers нет?из-за типа поля?выходит их нужно просто сопоставлять по названиям столбцов?мне кажется это нерационально и вообще не правильно...
и в Orders нет ни одного столбца из Shippers.как их тогда сопоставлять?
ЗЫ:может это излишне и есть какойто более простой метод? |
