把查询结果转换成xml格式，最后一句是转换成1,2,3这种形式，不做解释直接上代码。
1 SELECT * FROM student FOR xml path
结果
<row>
<Id>1</Id>
<Realname>小王</Realname>
<Sex>0</Sex>
</row>
<row>
<Id>2</Id>
<Realname>小张</Realname>
<Sex>0</Sex>
</row>
<row>
<Id>3</Id>
<Realname>小陈</Realname>
<Sex>0</Sex>
</row>
<row>
<Id>4</Id>
<Realname>小郑</Realname>
<Sex>0</Sex>
</row>
<row>
<Id>5</Id>
<Realname>小黑</Realname>
<Sex>0</Sex>
</row>
2 SELECT * FROM student FOR xml raw
结果
<row Id="1" Realname="小王" Sex="0"/>
<row Id="2" Realname="小张" Sex="0"/>
<row Id="3" Realname="小陈" Sex="0"/>
<row Id="4" Realname="小郑" Sex="0"/>
<row Id="5" Realname="小黑" Sex="0"/>
3 SELECT * FROM student FOR xml raw('student'),root('students')
结果
<students>
<student Id="1" Realname="小王" Sex="0"/>
<student Id="2" Realname="小张" Sex="0"/>
<student Id="3" Realname="小陈" Sex="0"/>
<student Id="4" Realname="小郑" Sex="0"/>
<student Id="5" Realname="小黑" Sex="0"/>
</students>
4 SELECT * FROM student FOR xml raw,elements
结果
<students>
<student Id="1" Realname="小王" Sex="0"/>
<student Id="2" Realname="小张" Sex="0"/>
<student Id="3" Realname="小陈" Sex="0"/>
<student Id="4" Realname="小郑" Sex="0"/>
<student Id="5" Realname="小黑" Sex="0"/>
</students>
5 SELECT STUFF((SELECT ',' + Realname FROM student FOR xml path('')),1,1,'') AS Names
结果
小王,小张,小陈,小郑,小黑