Error while modifying the Table in SQL Express Edition 2005

i want to modify my table in sql express edition.. after the modification, i also have chnged my primary key.. but when saving the modified table, it gives error that :

RegistrationForm' table - Unable to modify table.

Cannot insert the value NULL into column 'ID', table 'StudentRegistration.dbo.Tmp_RegistrationForm'; column does开发者_如何学Python not allow nulls. INSERT fails. The statement has been terminated.

Table def and ddl query might help but try setting a default value of 0, or start by creating the column as nullable, then populate it and change to non nullable.

That indicates that your changes would result in existing rows failing the constraints on NULL values.

Have you added the ID column?

If so, looks like it may be a primary key. If it is an int/numeric, you should probably turn on Identity Seeding.