Параметр не имеет значения по умолчанию

productParameterDataAdpter.DeleteCommand = new OleDbCommand(
    "DELETE FROM [Parameter Group] WHERE ([Group code] = @groupCode) AND ([Parameter code] = @parCode)", newConn); 
                    
OleDbParameter parCodePar = new OleDbParameter("@parCode",OleDbType.Integer);
normPar2.SourceColumn  = "Код параметра";
productParameterDataAdpter.DeleteCommand.Parameters.Add(parCodePar);
                        
OleDbParameter newGroupCodePar = new OleDbParameter("@groupCode", comboBox2.SelectedValue);
productParameterDataAdpter.DeleteCommand.Parameters.Add(newGroupCodePar).Value = comboBox2.SelectedValue;

productParameterDataAdpter.Update(journalDS, "SpecificParameters");

 System.Data.OleDb.OleDbDataAdapter productParameterDataAdpter=new OleDbDataAdapter();
            productParameterDataAdpter.DeleteCommand=new OleDbCommand("DELETE FROM [Parameter Group] WHERE ([Group code] = {0}) AND ([Parameter code] = @parCode)", newConn); 
 
            //Надо обновить
            productParameterDataAdpter.DeleteCommand.CommandText=
                String.Format(productParameterDataAdpter.DeleteCommand.CommandText,comboBox2.SelectedValue);