How can I update an xml node than contains another node with a specific value XML in sql server

Question

Example

declare @x xml;

set @x = N'
<Root>
  <Book>
     <ID>1</ID>
     <Price>100</Price>
     <Title>false</Title>
  </Book>
  <Book>
        <ID>2</ID>
        <Price>200</Price>
        <Price>false</Price>
  </Book>
  <Book>
        <ID>3</ID>
        <Price>300</Price>
        <Title>false</Title>
   </Book>
   <Book>
        <ID>4</ID>
        <Price>400</Price>
        <Title>false</Title>
   </Book>
</Root>'

Query to select the node that contains a child node with id =3

SELECT
@tmp = a.b.query('../.') 
from @x.nodes('//Book/ID[text()="3"]') a(b)

How can i modify the Price value of the selected node?

Answer 1

Consider using SQL Server's XML Data Modification Language (DML) , specifically the replace value of method. Below example updates Price to 9999:

declare @x xml;

set @x = N'
<Root>
  <Book>
     <ID>1</ID>
     <Price>100</Price>
     <Title>false</Title>
  </Book>
  <Book>
        <ID>2</ID>
        <Price>200</Price>
        <Price>false</Price>
  </Book>
  <Book>
        <ID>3</ID>
        <Price>300</Price>
        <Title>false</Title>
   </Book>
   <Book>
        <ID>4</ID>
        <Price>400</Price>
        <Title>false</Title>
   </Book>
</Root>'

set @x.modify('replace value of (/Root/Book[ID="3"]/Price/text())[1] with ("9999")')

select @x