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.

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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.

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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.