SQL: How to create a 1:1 relation?

[King_of_Queens]

Hello i serach for an sql command which creates a 1:1 relation in an access database. I think i can do this wiht CONSTRAINT but how? In the access help i found this: CREATE TABLE Bestell (BestellId INTEGER PRIMARY KEY, KundId INTEGER, BestellNotiz NCHAR VARYING (255), CONSTRAINT FKBestellKundId FOREIGN KEY (KundId) REFERENCES Kunden ON UPDATE CASCADE ON DELETE CASCADE but this creates only 1:N relation!

[Mike Dimmick]

Add a UNIQUE constraint to KundId?