Question

I am using SQL Server Management Studio connected to SQL Server 2008 R2.

• I have a table called User with a column Id (uniqueidentifier)
• I have a table called Role with a column Id (uniqueidentifier)
• I want a table called UserRolePair with 2 columns: UserId and RoleId.

I need each row to be unique (no duplicate roles for each user).

This is easy – I just right-click, choose Indexes & Keys and create a new unique key, that is comprised of both columns.

Now what I need to do – is to create a foreign key from UserId to the Id column of the User table, and create a foreign key from RoleId to the Id column of the Role table.

But when I choose Relationships from the sub-menu – I get this:

First of all – why do I have 2 relationships here ??

Second of all – when I want to create a new foreign key now for each column separately I get this:

I can’t choose to RoleId the Id column of the Role table !

It says I need to assign both columns of UserRole table with foreign keys from the same table.

What is the solution ?

Is the ‘unique’ what’s causing my problems ?

Answer 1

Your best bet is to use T-SQL statements instead of struggling with the visual designers.

a) create foreign key from UserRolePair to Role:

ALTER TABLE dbo.UserRolePair
ADD CONSTRAINT FK_UserRolePair_Role
FOREIGN KEY (RoleID) REFERENCES dbo.Role(ID)

b) create foreign key from UserRolePair to User:

ALTER TABLE dbo.UserRolePair
ADD CONSTRAINT FK_UserRolePair_User
FOREIGN KEY (UserID) REFERENCES dbo.User(ID)

Just execute those in a query window (make sure to be in the right database!) and you’re done!