Question

I have a table named myTable on SQL Server 2008 R2 Express.

I would like to have a (marital) Status column with the only explicit values: ‘Single’, ‘Married’, ‘Divorced’, ‘Widower’.
The default should be ‘Married’.

Is there a way to limit the field to the above values ON THE SQL Server without additional tables?

Answer 1

You can do that with a CHECK() constraint.

create table whatever (
...
  Status varchar(12) not null default 'Married' 
    check (Status in ('Single', 'Married', 'Divorced', 'Widower')),
...
);

The problem with using a CHECK constraint like this is that it’s harder for the user interface to present a list of valid choices to the user for selection. If these four were stored in a table of marital statuses, you could just select status from marital_statuses order by status;. If they were stored in a table, you could still use ‘Married’ as the default.

If I were going to store these in a table, it might look like this.

create table marital_statuses (
  status_code char(1) primary key,
  status_text varchar(12) not null unique
);

insert into marital_statuses values
('s', 'Single'),
('m', 'Married'),
('d', 'Divorced'),
('w', 'Widower');

Using human-readable codes means you usually won’t need an additional join. (If you use ID numbers, you always need an additional join.) If I did that, I’d use a foreign key in the “whatever” table, and change the default to ‘m’.