How Can I Create A One-to-one Relationship In A SQL Server Management Studio Express Relationship Diagram?

How can I create a one-to-one relationship in a SQL Server Management Studio Express Relationship diagram?

For example:
I have 2 tables, tbl1 and tbl2.

tbl1 has the following columns:
id {uniqueidentifier} as PK
name {nvarchar(50)}

tbl2 has the following columns:
id {uniqueidentifier} as PK
name {nvarchar(50)}
tbl1_id {uniqueidentifier} as FK linked to tbl1.id


If I drag and drop the tbl1.id column to tbl2 I end up with a one-to-many relationship. How do I create a one-to-one relationship instead?

mradlmaier