SQL XML DELETE

--A. 从存储在非类型化的 xml 变量中的文档中删除节点
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. 从存储在非类型化的 xml 列中的文档中删除节点
delete XML DML 语句从存储在列中的文档中删除 <Features> 的第二个子元素。
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，query返回Features元素下的所有节点,以XML格式返回
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 #T
DROP TABLE #T
C. 从非类型化的 xml 列中删除节点
create table #T(ProductModelID int primary key,
Instructions xml )
go
insert  #T
select ProductModelID, Instructions
from Prod