SQL主鍵的外鍵問題

Question

我在連接MSSQL Management studio的兩個表時遇到問題。 我的目標是通過外鍵連接表，如果我刪除用戶，我想第二個表條目將被自動刪除。我打算使用DELETE Cascade方法。

User: 
CREATE TABLE [dbo].[Users](
[ID] [bigint] IDENTITY(1,1) NOT NULL, 
[Email] [nvarchar](89) NOT NULL, 
[Name] [nvarchar](25) NOT NULL, 
[Midname] [nvarchar](25) NOT NULL, 
[Surname] [nvarchar](25) NOT NULL, 
[Phone] [varchar](15) NOT NULL, 
[Country] [smallint] NOT NULL, 
[Manager] [nvarchar](89) NOT NULL, 
[Referrer] [nvarchar](89) NOT NULL, 
[Rank] [tinyint] NOT NULL, 
CONSTRAINT [PK_Users] PRIMARY KEY CLUSTERED 
(
[Email] 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 

電子郵件是主鍵

Payments: 
CREATE TABLE [dbo].[Investments](
[ID] [bigint] NOT NULL, 
[Investor] [nvarchar](89) NOT NULL, 
[Sum] [decimal](19, 4) NOT NULL, 
[Currency] [smallint] NOT NULL, 
[Credit] [decimal](19, 4) NOT NULL, 
[CreditRate] [decimal](19, 4) NOT NULL, 
[Rate] [tinyint] IDENTITY(1,1) NOT NULL, 
[Date] [smalldatetime] NOT NULL, 
[Comment] [nvarchar](max) NOT NULL, 
CONSTRAINT [PK_Investments] PRIMARY KEY CLUSTERED 
(
     [ID] 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 

ID是主鍵

我FK應該像USER->付款或付款 - >用戶？

當我試圖連接的用戶 - 使用foregn鍵通過電子郵件>付款 - >投資者，它告訴我，這樣的錯誤：

The columns in table 'Payments' do not match an existing primary key or UNIQUE constraint.

能否請你解釋一下我在哪裏的問題是什麼？我做錯了什麼？

Answer 1

你的結構變更爲：

CREATE TABLE [dbo].[Users](
[ID] [bigint] IDENTITY(1,1) NOT NULL, 
[Email] [nvarchar](89) NOT NULL, 
[Name] [nvarchar](25) NOT NULL, 
[Midname] [nvarchar](25) NOT NULL, 
[Surname] [nvarchar](25) NOT NULL, 
[Phone] [varchar](15) NOT NULL, 
[Country] [smallint] NOT NULL, 
[Manager] [nvarchar](89) NOT NULL, 
[Referrer] [nvarchar](89) NOT NULL, 
[Rank] [tinyint] NOT NULL); 

ALTER TABLE [Users] 
ADD CONSTRAINT PK_UsersID PRIMARY KEY (ID); 

然後

CREATE TABLE [dbo].[Investments](
[ID] [bigint] NOT NULL, 
[UserID] [bigint] NOT NULL, 
[Sum] [decimal](19, 4) NOT NULL, 
[Currency] [smallint] NOT NULL, 
[Credit] [decimal](19, 4) NOT NULL, 
[CreditRate] [decimal](19, 4) NOT NULL, 
[Rate] [tinyint] IDENTITY(1,1) NOT NULL, 
[Date] [smalldatetime] NOT NULL, 
[Comment] [nvarchar](max) NOT NULL); 

ALTER TABLE Investments 
ADD CONSTRAINT PK_InstestmentsID PRIMARY KEY (ID); 

ALTER TABLE Investments 
ADD CONSTRAINT FK_UsersInvestments 
FOREIGN KEY (UserID) 
REFERENCES Users(ID); 

然後加入上Investments.UserID

Answer 2

我搜索您所看到的錯誤消息（沒有表名）和普遍的共識 似乎是一個PRIMARY KEY或UNIQUE contraint未正確在表設置。該錯誤還告訴我你（可能）使用SQL Server。

從technet.microsoft.com：

The columns on the primary key side of a foreign key relationship must participate in either a Primary Key or a Unique Constraint. After setting up a Primary Key or a Unique constraint for one of the tables you've selected, you can then define other relationships for that table.

檢查PRIMARY KEYS兩表所示。如果沒有桌面的實際DDL，很難獲得更多幫助。

編輯：你Email在你Users表PRIMARY KEY，但我沒有看到在Investments表的Email場。你在哪些領域加入你的禁忌？