Code in Visual C++ for adding a field to a table with default value

Question

I'd like to insert a new field with a Default value using Visual C++ Code. I have wrote this, but it doesn't function as I want:

CADODatabase pDB; String strConnessione = _T("Provider=Microsoft.Jet.OLEDB.4.0;""Data Source="); strConnessione = strConnessione + "MyDatabase.mdb"; pDB.SetConnectionString(strConnessione); pDB.Open();

query.Format("ALTER TABLE TBProva ADD Fattore Double Default 0;"); pDB.Execute(query);

How can I do for doing it? Is very important for me, please help.... Someone of you can write me the just code? Thank you