Default constraints and values

Hi,

Does anyone know why I am able to create a table such as follows?

create table test
(col1 nvarchar(1) default 'AA',
col2 nvarchar(1) null)
go

Notice that I have a default value of 'AA' for a column that is defined as
an nvarchar(1). SQL Server created the table without any errors.

Of course, when I try to do an insert without specifying the column so that
the default value would kick in, it gives me an error.

insert into test
(col2)
values
('A')
go

Server: Msg 8152, Level 16, State 4, Line 1
String or binary data would be truncated.
The statement has been terminated.

Thanks,
Dee

>> Does anyone know why I am able to create a table such as follows?

CREATE TABLE Test
(col1 NVARCHAR(1) DEFAULT 'AA',
col2 NVARCHAR(1));

Notice that I have a DEFAULT of 'AA' for a column that is defined as
an NVARCHAR(1). SQL Server created the table without any errors. f
course, when I try to do an insert without specifying the column so
that the default value would kick in, it gives me an error. <<

There is no validation on a DEFAULT until run time. This is just SQL
Server; other SQL products handle it differently. I am not sure about
2008, but you used to be able to give a DEFAULT of a different but
CAST-able data type -- say INTEGER value to a REAL -- and it would
force the engine to constantly CAST the value on insertion.