如何通过XQuery在SQL中使用节点的当前值更改节点值(SQL Server) [英] How to change node value using node's current value in SQL with XQuery (SQL Server)

问题描述

如何更改:

<data>
  <row>
    <a>A</a>
    <a>B</a>
    <a>C</a>
  </row>
</data>

收件人:

<data>
  <row>
    <a>Data A</a>
    <a>Data B</a>
    <a>Data C</a>
  </row>
</data>

在SQL中?我见过很多关于如何用静态值完全替换值的示例，但是没有动态替换值的示例.

in SQL? I've seen lots of examples on how to completely replace a value with a static value, but no examples of replacing the value dynamically.

推荐答案

我不知道是否可以在replace value of语句中使用xml.但是你可以做到这一点.

I do not know if it is possible to use the xml in the replace value of statement. But you can do this.

declare @xml xml = '
<data>
  <row>
    <a>A</a>
    <a>B</a>
    <a>C</a>
  </row>
</data>'

declare @Val1 varchar(10) 
declare @Val2 varchar(10) 
declare @Val3 varchar(10) 

select 
  @Val1 = 'Data '+r.value('a[1]', 'varchar(1)'), 
  @Val2 = 'Data '+r.value('a[2]', 'varchar(1)'), 
  @Val3 = 'Data '+r.value('a[3]', 'varchar(1)') 
from @xml.nodes('/data/row') n(r)

set @xml.modify('replace value of (/data/row/a/text())[1] with (sql:variable("@val1"))')
set @xml.modify('replace value of (/data/row/a/text())[2] with (sql:variable("@val2"))')
set @xml.modify('replace value of (/data/row/a/text())[3] with (sql:variable("@val3"))')

版本2

declare @xml xml = '
<data>
  <row>
    <a>A</a>
    <a>B</a>
    <a>C</a>
  </row>
  <row>
    <a>1</a>
    <a>2</a>
    <a>3</a>
  </row>
</data>'

;with cte as
(
  select
    r.query('.') as Row,
    row_number() over(order by (select 0)) as rn
  from @xml.nodes('/data/row') n(r)
)
select
  (select 
     'Data '+a.value('.', 'varchar(1)')
   from cte as c2
     cross apply Row.nodes('row/a') as r(a)
   where c1.rn = c2.rn
   for xml path('a'), root('row'), type)  
from cte as c1 
group by rn
for xml path(''), root('data')

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