不可能一次在多个地方更新 XML，因此您必须在某种循环中执行此操作.我能想到的***方法是从 Table2 中的 XML 中提取 ID 并与 Table1.ID 连接以生成一个包含 Table2.ID 的临时表 XML 中 Data1 节点的序号位置 (OrdPos) 和新的 GUID 值.

It is not possible to update the XML in more than one place at a time so you have to do this in a loop of some kind. The best I could come up with was to extract the ID's from the XML in Table2 and join against Table1.ID to produce a temp table that holds Table2.ID ordinal position of the Data1 node in the XML (OrdPos) and the new GUID value.

然后您可以遍历 XML 列中存在的最大节点数并进行更新.

Then you can loop over the max number of nodes present in the XML column and do the update.

-- Variable used to loop over nodes
declare @I int 

-- Temp table to hold the work that needs to be done.
create table #T
(
  ID int, -- ID from table2
  OrdPos int, -- Ordinal position of node Data1 in root
  GUID uniqueidentifier, -- New ID
  primary key (OrdPos, ID)
)

-- Shred the XML in Table2, join to Table1 to get GUID
insert into #T(ID, OrdPos, GUID)
select T2.ID,
       row_number() over(partition by T2.ID order by D.N) as OrdPos,
       T1.GUID
from Table2 as T2
  cross apply T2.XMLCol.nodes('Root[1]/Data1') as D(N)
  inner join Table1 as T1
    on T1.ID = D.N.value('(ID/text())[1]', 'int')

-- Get the max number of nodes in one row that needs to be updated
set @I = 
  (
    select top(1) count(*)
    from #T
    group by ID
    order by 1 desc
  )

-- Do the updates in a loop, one level at a time
while @I > 0
begin
  update T2
  set XMLCol.modify('replace value of (/Root[1]/Data1[sql:variable("@I")]/ID/text())[1] 
                     with sql:column("T.GUID")')
  from Table2 as T2
    inner join #T as T
      on T2.ID = T.ID
  where T.OrdPos = @I

  set @I = @I - 1
end

drop table #T

SQL 小提琴