protected override void RegisterRelationValue(RelationRowCreationResource res, String columnName)
        {
            IPropertyType pt    = res.CurrentPropertyType;
            Object        value = null;

            if (res.ContainsRelKeyValueIfExists(columnName))
            {
                // if this column is relation key, it gets the value from relation key values
                // for performance and avoiding twice getting same column value
                value = res.ExtractRelKeyValue(columnName);
            }
            else
            {
                IValueType         valueType      = pt.ValueType;
                Map <String, int?> selectIndexMap = GetSelectIndexMap();
                if (selectIndexMap != null)
                {
                    value = GetValue(res.DataReader, columnName, valueType, selectIndexMap);
                }
                else
                {
                    value = valueType.GetValue(res.DataReader, columnName);
                }
            }
            if (value != null)
            {
                res.IncrementValidValueCount();
                DBMeta dbmeta       = FindDBMeta(res.Row);
                String propertyName = pt.PropertyName;
                if (dbmeta != null && dbmeta.HasEntityPropertySetupper(propertyName))
                {
                    dbmeta.SetupEntityProperty(propertyName, res.Row, value);
                }
                else
                {
                    PropertyInfo pd = pt.PropertyInfo;
                    pd.SetValue(res.Row, value, null);
                }
            }
        }