title: SQL Server UniqueIdentifier as FK
body: <p>I am trying to execute the following but its giving an error  of, I tried doing it with designer, same error saying data type, precision and length must be the same, even though they are</p>
  
  <pre><code>ALTER TABLE CustomerUsers
  ADD CONSTRAINT fk_CustomerUsers_Users
  FOREIGN KEY (CustomerID)
  REFERENCES Customers(UniqueID)
  </code></pre>
  
  <p><strong>Error thrown:</strong></p>
  
  <blockquote>
  <pre><code>Msg 1769, Level 16, State 1, Line 1
  Foreign key 'fk_CustomerUsers_Users' references invalid column 'UniqueID' in referencing table 'CustomerUsers'.
  Msg 1750, Level 16, State 0, Line 1
  Could not create constraint. See previous errors.
  </code></pre>
  </blockquote>
  
  <p>Here is My Table Structure.</p>
  
  <pre><code>CREATE TABLE [dbo].[Customers](
  [CustomerID] [int] IDENTITY(1,1) NOT NULL,
  [Name] [nvarchar](500) NOT NULL,
  [ContentLocation] [nvarchar](500) NOT NULL,
  [UniqueID] [uniqueidentifier] NOT NULL,
  CONSTRAINT [PK_Customers] PRIMARY KEY CLUSTERED 
  (
  [CustomerID] ASC
   )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF,IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
  ) ON [PRIMARY]
  
  
  CREATE TABLE [dbo].[CustomerUsers](
  [CustomerUserID] [int] IDENTITY(1,1) NOT NULL,
  [CustomerUniqueID] [uniqueidentifier] NOT NULL,
  [UserID] [nvarchar](128) NOT NULL,
  CONSTRAINT [PK_CustomerUsers] PRIMARY KEY CLUSTERED 
  (
  [CustomerUserID] 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
  
  ALTER TABLE [dbo].[CustomerUsers]  WITH CHECK ADD  CONSTRAINT [FK_CustomerUsers_AspNetUsers] FOREIGN KEY([UserID])
  REFERENCES [dbo].[AspNetUsers] ([Id])
  GO
  
  ALTER TABLE [dbo].[CustomerUsers] CHECK CONSTRAINT [FK_CustomerUsers_AspNetUsers]
  GO
  </code></pre>