Re: indices and char(0) and unique constraints

[Jochen Wiedmann]

Dodger wrote:

> I wanted to create a char(0) with a unique constraint, intending thus to
> build into a table a sort of 'selector' -- where only one row could have the
> column defined as not null, forcing the rest to remain null (because '' is
> the only non-null value possible, and if it had to be unique, only one
> column could contain that value).


IMO this would restrict your table to have at most
two rows. Is this what you intend=