SQL Server:OPENXML与SELECT..FROM处理XML时?

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我有这个xml:
DECLARE @x XML
SET @x = 
    '<data>
       <add>a</add>
       <add>b</add>
       <add>c</add>
     </data>';

任务:

我想列出a,b,c.

方法1:

SELECT s.value('.','VARCHAR(8000)') AS [ADD]
FROM   @x.nodes('/data/add') AS t(s)

方法2:

DECLARE @idoc INT
EXEC sp_xml_preparedocument @idoc OUTPUT,@x

SELECT *
FROM   OPENXML(@idoc,'/data/add',2)
       WITH ([add] NVARCHAR(MAX) '.')

他们都给我:

题 :

哪个是首选方式?

后者与前者(或副经文)有什么优势吗?

解决方法

一个简单的测试表明,您的方法1比方法2花费的时间更少.我不会总结这样的结论.它可以依赖于XML的结构以及您如何查询XML.

存储程序测试:

create procedure TestXML
  @X xml
as
set nocount on

select X.N.value('.','varchar(8000)')
from @X.nodes('/root/item') as X(N)

go

create procedure TestOpenXML
  @X xml
as
set nocount on

declare @idoc int
exec sp_xml_preparedocument @idoc out,@X

select value
from openxml(@idoc,'/root/item',1) 
  with (value  varchar(8000) '.')

exec sp_xml_removedocument @idoc

测试:

declare @X xml

set @X =
  (
    select number as '*'
    from master..spt_values
    for xml path('item'),root('root'),type
  )

set statistics time on
exec TestXML @X
exec TestOpenXML @X

结果方法1:

sql Server Execution Times:
   cpu time = 63 ms,elapsed time = 70 ms.

结果方法2:

sql Server Execution Times:
   cpu time = 156 ms,elapsed time = 159 ms.

(在sql Server 2005上测试.)

原文链接:https://www.f2er.com/mssql/75520.html

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