A. Deleting nodes from a document stored in an untyped xml variable
The following example illustrates how to delete various nodes from a document. First, an XML instance is assigned to variable of xml type. Then, subsequent delete XML DML statements delete various nodes from the document.
DECLARE @myDoc xml
SET @myDoc = '<?Instructions for=TheWC.exe ?>
<Root>
<!-- instructions for the 1st work center -->
<Location LocationID="10"
LaborHours="1.1"
MachineHours=".2" >Some text 1
<step>Manufacturing step 1 at this work center</step>
<step>Manufacturing step 2 at this work center</step>
</Location>
</Root>'
SELECT @myDoc
-- delete an attribute
SET @myDoc.modify('
delete /Root/Location/@MachineHours
')
SELECT @myDoc
-- delete an element
SET @myDoc.modify('
delete /Root/Location/step[2]
')
SELECT @myDoc
-- delete text node (in <Location>
SET @myDoc.modify('
delete /Root/Location/text()
')
SELECT @myDoc
-- delete all processing instructions
SET @myDoc.modify('
delete //processing-instruction()
')
SELECT @myDoc
B. Deleting nodes from a document stored in an untyped xml column
In the following example, a delete XML DML statement removes the second child element of <Features> from the document stored in the column.
CREATE TABLE T (i int, x xml)
go
INSERT INTO T VALUES(1,'<Root>
<ProductDescription ProductID="1" ProductName="Road Bike">
<Features>
<Warranty>1 year parts and labor</Warranty>
<Maintenance>3 year parts and labor extended maintenance is available</Maintenance>
</Features>
</ProductDescription>
</Root>')
go
-- verify the contents before delete
SELECT x.query(' //ProductDescription/Features')
FROM T
-- delete the second feature
UPDATE T
SET x.modify('delete /Root/ProductDescription/Features/*[2]')
-- verify the deletion
SELECT x.query(' //ProductDescription/Features')
FROM TNote the following from the previous query:
C. Deleting nodes from a typed xml column
This example deletes nodes from a manufacturing instructions XML document stored in a typed xml column.
In the example, you first create a table (T) with a typed xml column in the AdventureWorks database. You then copy a manufacturing instructions XML instance from the Instructions column in the ProductModel table into table T and delete one or more nodes from the document.
use AdventureWorks
go
drop table T
go
create table T(ProductModelID int primary key,
Instructions xml (Production.ManuInstructionsSchemaCollection))
go
insert T
select ProductModelID, Instructions
from Production.ProductModel
where ProductModelID=7
go
select Instructions
from T
--1) insert <Location 1000/>. Note: <Root> must be singleton in the query
update T
set Instructions.modify('
declare namespace MI="http://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelManuInstructions";
insert <MI:Location LocationID="1000" LaborHours="1000" >
These are manu steps at location 1000.
<MI:step>New step1 instructions</MI:step>
Instructions for step 2 are here
<MI:step>New step 2 instructions</MI:step>
</MI:Location>
as first
into (/MI:root)[1]
')
go
select Instructions
from T
-- delete an attribute
update T
set Instructions.modify('
declare namespace MI="http://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelManuInstructions";
delete(/MI:root/MI:Location[@LocationID=1000]/@LaborHours)
')
go
select Instructions
from T
-- delete text in <location>
update T
set Instructions.modify('
declare namespace MI="http://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelManuInstructions";
delete(/MI:root/MI:Location[@LocationID=1000]/text())
')
go
select Instructions
from T
-- delete 2nd manu step at location 1000
update T
set Instructions.modify('
declare namespace MI="http://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelManuInstructions";
delete(/MI:root/MI:Location[@LocationID=1000]/MI:step[2])
')
go
select Instructions
from T
-- cleanup
drop table T
go