Sql Xquery How to Replace text in Update Query

Harsh Baid picture Harsh Baid · Feb 23, 2011 · Viewed 12.6k times · Source

Table is named as MasterTable

Columns

ID type BIGINT,

Name type VARCHAR(200) (stores xml type data for some reasons)

Name contains data structured as

<en-US>SomeEnglishText</en-US><it-IT>SomeItalicText</it-IT>

When I need to Update the Master Table then at that time I Need to cast the Varchar to xml then conditionally update / replace the value part of particular tag i.e either en-US / it-IT.

Also there are chances that No data/tags are there in Name column so I think at the time of Inserting data it would Insert empty tag elements in the table like <en-US></en-US><it-IT></it-IT>, so the update query must handle empty value in tag elements namely en-US/it-IT.

I am trying to do it like following update query.

DECLARE @Str VARCHAR(200)

SET @Str = 'Test Text'

UPDATE [MasterTable]
SET [Name] = cast([MasterTable].[Name] as xml).modify('replace value of (en-US/text())[1] with sql:variable("@Str")')
WHERE [ID]=18

I getting following error when running the query

Illegal use of xml data type method 'modify'. A non-mutator method is expected in this context.

Answer

Mikael Eriksson picture Mikael Eriksson · Feb 23, 2011

You can not assign from a xml.modify. Modify works on the variable/column directly. You can also not use modify on a cast.

You can extract the name to a xml variable, modify the xml and then put it back to the table.

declare @str varchar(200) = 'Test'
declare @xml xml

select @xml = cast(Name as xml)
from MasterTable
where ID = 18

set @xml.modify('replace value of (en-US/text())[1] with sql:variable("@Str")')

update MasterTable
set Name = cast(@xml as varchar(200))
where ID = 18

If you need this to work over more than one row at a time you can use a table variable with columns id and name where data type for name is xml instead of the @xml variable.

declare @str varchar(200) = 'Test Text'
declare @T table (ID int, Name xml)

insert into @T
select ID, cast(Name as xml)
from MasterTable
where Name is not null

update @T
set Name.modify('replace value of (en-US/text())[1] with sql:variable("@Str")')

update MasterTable
set Name = cast(T.Name as varchar(200))
from @T as T
where MasterTable.ID = T.ID