SQL Foreign key issue with Primary Keys - sql

Question

I do have a problem connecting two tables on MSSQL Management studio.
My goal is connect tables by foreign key and if I delete user I want 2nd table entry will be deleted automatically. I plan to use DELETE Cascade method for that.
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
Email is Primary key
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 is Primary key
My FK should be like USER->PAYMENTS or PAYMENTS->USER?
When I am trying to connect User -> Payments using foregn key by Email -> Investor, it tell me such error:
The columns in table 'Payments' do not match an existing primary key or UNIQUE constraint.
Could you please explain me where problem is? And what I am doing wrong?

Answer 1

Change your structure to:
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);
and then
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);
Then join Users.ID on Investments.UserID

Answer 2

I searched for the error message you are seeing (without the table name) and the general consensus
seems to be that a PRIMARY KEY or UNIQUE contraint has not been correctly set in your tables. The error also tells me you are (probably) using SQL Server.
From 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.
Check your PRIMARY KEYS in both tables. Without the actual DDL of your tables it's difficult to be of more help.
EDIT: You have Email as the PRIMARY KEY in your Users table but I do not see an Email field in the Investments table. Which fields are you joining on in your contraint?