To create a new default and also seed with the WITH VALUES clause only works when adding a new column, not when changing an existing column.

What you need to do is three things.

Add the default

Update the column to the default value where it is null.

Alter the column to not null

The first two steps can be done in any order.

ALTER TABLE DATA

add constraint DF_IsTested DEFAULT(0) FOR IsTested

GO

UPDATE DATA

SET    IsTested = 0

WHERE  IsTested IS NULL

GO

ALTER TABLE DATA

ALTER COLUMN [IsTested] [bit] NOT NULL

GO

/Kenneth