>>If my field can be either Y or N, how can I specify it? Or if the field can be only one of 3 predefined values?
>
>Do you want to limit the column to only containing one of those discrete values? If so, you'll want to add a CHECK constraint to the table:
>
>CREATE TABLE mytable (
> gender nchar(1) CHECK(gender IN ('m', 'f'))
>...
>)
>

Can I do it in designer? I already created tables...

I put it in designer, but it doesn't look, like it was created. E.g. in the script of table Creation I don't see it. Is it correct to do in table designer managing constraints?