Consider the following table structure:
Id uniqueidentifier
ControlId bigint
Number tinyint
field_0 varchar(10)
field_1 varchar(10)
.
.
field_n varchar(10)

The Id field is my PK, but I would also like to add a unique constraint on the "combination" of the fields ControlId and Number. How can I do this? Please let me know if what I am asking is very unclear.

Thanks,
Einar