nullable_2.xml

<dataset>
    <t_order order_id="1200" sku_num="0" status="init" />
    <t_order order_id="1201" sku_num="1" status="init" />
    <t_order order_id="2200" sku_num="2" status="init" />
    <t_order order_id="2201" sku_num="3" status="init" />
</dataset>