用法： FOR XML PATH 方法是用于将查询结果集以XML形式展示
sql:
select top 5 p.ContactTypeID,p.ModifiedDate,p.Name from [Person].[ContactType] p for xml path
显示结果：
<row>
<ContactTypeID>1</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Accounting Manager</Name>
</row>
<row>
<ContactTypeID>2</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Assistant Sales Agent</Name>
</row>
<row>
<ContactTypeID>3</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Assistant Sales Representative</Name>
</row>
<row>
<ContactTypeID>4</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Coordinator Foreign Markets</Name>
</row>
<row>
<ContactTypeID>5</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Export Administrator</Name>
</row>
path的用法：用来指定行结点，如果不指定行节点，默认使用'row',
sql:
select top 5 p.ContactTypeID,p.ModifiedDate,p.Name from [Person].[ContactType] p for xml path('AA')
显示结果：
<AA>
<ContactTypeID>1</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Accounting Manager</Name>
</AA>
<AA>
<ContactTypeID>2</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Assistant Sales Agent</Name>
</AA>
<AA>
<ContactTypeID>3</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Assistant Sales Representative</Name>
</AA>
<AA>
<ContactTypeID>4</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Coordinator Foreign Markets</Name>
</AA>
<AA>
<ContactTypeID>5</ContactTypeID>
<ModifiedDate>2002-06-01T00:00:00</ModifiedDate>
<Name>Export Administrator</Name>
</AA>
下来来利用 for xml path 输出结果就是一行字符串，如果去掉行节点就可以把整列的结果输出一行，
sql :
select top 5 '['+ p.Name+']' from [Person].[ContactType] p for xml path('')
显示结果： [Accounting Manager][Assistant Sales Agent][Assistant Sales Representative][Coordinator Foreign Markets][Export Administrator]
这个可用来 一行来显示明细表中的信息，通常主表和细表是一对多的关系，把细表中的多用 for xml path 输出为一列，加到主表中一起输出。