using identity

[DangerM0use]

I am using identity so that everytime a new entry is entered into the db it automatially chooses the next available number

Type_# int not null identity(1,1),

I am just wondering if it is a good idea to have a constraint as well to make sure the number is in a set limit, so for example;

constraint Type_# check (Type_# between '000000' and '999999'),

Cheers