Запись поля datetime в БД - дата не записывается

string format = "yyyy-MM-dd";
DateTime CreateDTzap = DateTime.Now.Date;
string dt = "2012-12-12 12:00:00.000";
SqlConnection cnw = new SqlConnection("Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=base;Data Source=sql1.qwe.local");
SqlCommand cmd = new SqlCommand();
cmd.Connection = cnw;
cnw.Open();
cmd.CommandText = @"INSERT INTO dbo.qwe (CreateDTzap) VALUES ("+dt+")";
cmd.ExecuteNonQuery();
cmd.Clone();

string format = "'yyyy-MM-dd hh:mm:ss.nnn'";
DateTime CreateDTzap = DateTime.Now.Date;
cmd.CommandText = @"INSERT INTO dbo.qwe (CreateDTzap) 
               VALUES (" + CreateDTzap.ToString(format) + ")";

cmd.CommandText = @"INSERT INTO dbo.qwe (CreateDTzap) VALUES (CURRENT_TIMESTAMP)";

....
cmd.CommandText = @"INSERT INTO dbo.qwe (CreateDTzap) VALUES (@dt)";
cmd.Parameters.Add("@dt", DateTime.Now.Date);
cmd.ExecuteNonQuery();
....

 SqlCommand sqlCm = new SqlCommand("INSERT INTO TableParty (DateTime) VALUES (@DateTime)", sqlCn);
            SqlParameter sqlP = new SqlParameter();
            sqlP.ParameterName = "@DateTime";
            sqlP.Value = DateTime.Now.Date;
            sqlP.SqlDbType = SqlDbType.DateTime;
            sqlCm.Parameters.Add(sqlP);

sqlP.Value = DateTime.Now;