参考：https://blog.csdn.net/hliq5399/article/details/8315373

xml字段的格式：

<OuterCheckRet xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <JXZK>1</JXZK>
  <PQWRKZZZ>1</PQWRKZZZ>
  <RYXTDKB>1</RYXTDKB>
  <SJYHZMHY>0</SJYHZMHY>
  <QZXTFXT>1</QZXTFXT>
  <RYZFKZXT>1</RYZFKZXT>
  <YBGZ>1</YBGZ>
  <JXGZ>0</JXGZ>
  <JPQXTXL>0</JPQXTXL>
  <YTSL>0</YTSL>
  <OBDXT>0</OBDXT>
  <LTQY>1</LTQY>
  <LTGZQJ>1</LTGZQJ>
  <GBFSSB>1</GBFSSB>
  <ZDYXGN>1</ZDYXGN>
  <YXYP>0</YXYP>
  <GKFJC>0</GKFJC>
</OuterCheckRet>

我要修改GKFJC节点的值，如下：

declare @xmlDoc xml;
select @xmlDoc= OuterCheckRet from Det_OuterData outd,Det_Summary summ 
where outd.DetLsh=summ.DetLsh and summ.JCFFID='S'--双怠速
set @xmlDoc.modify('replace value of (/OuterCheckRet/GKFJC/text())[1] with "0"')--否
update Det_OuterData set OuterCheckRet=Convert(nvarchar(max),@xmldoc) 
where DetLsh in (select outd.DetLsh from Det_OuterData outd,Det_Summary summ 
where outd.DetLsh=summ.DetLsh and summ.JCFFID='S')

这样就修改了GKFJC节点的值了

==================================================
查询GKFJC节点的值，如下：

select (select OuterCheckRet from Det_OuterData where DetLsh='232701092009071010470008').value('(OuterCheckRet/GKFJC)[1]','varchar(10)') as ti