我创建了两个表。而且我需要在Friends
的第二张表中有两个ID。 UserId
来自UserInformation
表。 FriendId
已在此表中。我需要在这两个表之间建立关系并正确地制作FK和PK。我试图自己做,但它尖叫我在这里没做的 - 参考[UserInformation](UserId)
我需要你的帮助才能正确完成工作
CREATE TABLE [dbo].[UserInformation]
(
[Id] [INT] IDENTITY(1,1) NOT NULL,
[Login] [VARCHAR](50) NOT NULL,
[Password] [VARCHAR](50) NOT NULL,
[FirstName] [NCHAR](10) NOT NULL,
[LastName] [NCHAR](10) NOT NULL,
[Email] [VARCHAR](50) NOT NULL,
[RegistrationDate] [DATETIME] NOT NULL,
[Groups] [VARCHAR](50) NOT NULL
)
GO
CREATE TABLE [dbo].[Friends]
(
[UserId] [INT] NOT NULL,
[FriendId] [INT] NOT NULL,
PRIMARY KEY (FriendId),
CONSTRAINT FK_UserInformationFriend
FOREIGN KEY (UserId) REFERENCES [UserInformation](UserId)
)
GO
ALTER TABLE [dbo].[UserInformation]
ADD CONSTRAINT [DF_UserInformation_RegistrationDate]
DEFAULT (GETDATE()) FOR [RegistrationDate]
GO
ALTER TABLE UserInformation
ADD CONSTRAINT DF_UserInformation_Login_Unique UNIQUE(Login)
GO
ALTER TABLE UserInformation
ADD CONSTRAINT DF_UserInformation_Email_Unique UNIQUE(Email)
GO
ALTER TABLE UserInformation
ADD CONSTRAINT [PK_UserInformation] PRIMARY KEY ([Id])
GO
ALTER TABLE Friends
ADD CONSTRAINT [PK_Friends] PRIMARY KEY ([UserId])
GO
首先将其更改为:
CREATE TABLE [dbo].[UserInformation](
[Id] [int] IDENTITY(1,1) PRIMARY KEY NOT NULL,
[Login] [varchar](50) NOT NULL,
[Password] [varchar](50) NOT NULL,
[FirstName] [nchar](10) NOT NULL,
[LastName] [nchar](10) NOT NULL,
[Email] [varchar](50) NOT NULL,
[RegistrationDate] [datetime] NOT NULL,
[Groups] [varchar](50) NOT NULL
)
然后:
CREATE TABLE [dbo].[Friends](
[UserId] [int] NOT NULL,
[FriendId] [int] NOT NULL,
PRIMARY KEY (FriendId),
CONSTRAINT FK_UserInformationFriend FOREIGN KEY (UserId)
REFERENCES [UserInformation](Id)
)
和最后:
ALTER TABLE [dbo].[UserInformation]
ADD CONSTRAINT [DF_UserInformation_RegistrationDate] DEFAULT
(getdate()) FOR [RegistrationDate]
GO
ALTER TABLE UserInformation
ADD CONSTRAINT DF_UserInformation_Login_Unique UNIQUE (Login)
GO
ALTER TABLE UserInformation
ADD CONSTRAINT DF_UserInformation_Email_Unique UNIQUE (Email)
不需要这些,因为已经为两个表设置了主要:
ALTER TABLE UserInformation
ADD CONSTRAINT [PK_UserInformation] PRIMARY KEY ([Id])
GO
ALTER TABLE Friends
ADD CONSTRAINT [PK_Friends] PRIMARY KEY ([UserId])
GO
注意:如果您需要多个主键,那么请选择复合主键:
primary key (FriendId, UserId)