Memperbarui atribut Xml dengan nilai baru di tabel SQL Server 2008

Dari versi awal pertanyaan Anda, sepertinya XML Anda sebenarnya ada di baris yang berbeda dalam sebuah tabel. Jika demikian, Anda dapat menggunakan ini.

update YourTable set
  XMLText.modify('replace value of (/Identification/@Age)[1] with "40"')
where XMLText.value('(/Identification/@Age)[1]', 'int') = 30

Contoh kerja menggunakan variabel tabel.

declare @T table(XMLText xml)

insert into @T values('<Identification Name="John"  Family="Brown"   Age="30" />')
insert into @T values('<Identification Name="Smith" Family="Johnson" Age="35" />') 
insert into @T values('<Identification Name="Jessy" Family="Albert"  Age="60" />')
insert into @T values('<Identification Name="Mike"  Family="Brown"   Age="23" />')
insert into @T values('<Identification Name="Sarah" Family="Johnson" Age="30" />')

update @T set
  XMLText.modify('replace value of (/Identification/@Age)[1] with "40"')
where XMLText.value('(/Identification/@Age)[1]', 'int') = 30

select *
from @T