NULL NOT NULL on Default constraint in sql

Question

If I set a Record in Sql with a Default constraint like

[Publicbit]   BIT             DEFAULT ((0)),

Do I need to set the NULL/NOTNULL Constraint?

Edit: I am using a boolean but please expand your answer to other datatypes.

Answer 1

You never need the Null constraints, but the default value won't guard your table against explicit NULL's. So you should use a NOT NULL constraint if you want to enforce this condition.

use tempdb
go
CREATE TABLE example
(
    id BIT DEFAULT (0)
)

INSERT example (id) VALUES (null)

SELECT * FROM example