XmlDataDocument的问题.
XmlDataDocument a = new XmlDataDocument();
a.loadxml("<root></root>");
for循环
{
XmlDataDocument b = new XmlDataDocument();
b.loadxml("<record>...</record>");
--> 怎样把b写入a的<root>和</root>之间
}

最后a是
<root>
<record>...</record>
<record>...</record>
<record>...</record>
...
</root>

[解决办法]
XmlDataDocument类已过时，建议用XmlDocument。
如何创建xml，请参考：http://blog.csdn.net/chinacsharper/article/details/17268167