是否可以使用XML DML语句在未经类型定义的XML列中重命名元素?
我正在更新XML列上的XML模式集,并需要在应用最新模式之前通过重命名一个元素来修补现有的XML实例。
据我所知,根据文档,您只能插入/删除节点或替换其值。
是否可以使用XML DML语句在未经类型定义的XML列中重命名元素?
我正在更新XML列上的XML模式集,并需要在应用最新模式之前通过重命名一个元素来修补现有的XML实例。
据我所知,根据文档,您只能插入/删除节点或替换其值。
declare @xml as xml = '<animal species="Mouse">
<legs>
<leg>Front Right</leg>
<leg>Front Left</leg>
<leg>Back Right</leg>
<leg>Back Left</leg>
</legs>
</animal>'
set @xml = (select
t.c.value('@species', 'varchar(max)') as '@species'
,(select
ti.C.value('.', 'varchar(max)')
from @Xml.nodes('//animal/legs/leg') ti(c) for xml path('limb'), /* root('limb'), */type) as limbs
from @xml.nodes('//*:animal') t(c) for xml path('animal'), type)
select @xml;
while (@xml.exist('/animal/limbs/limb') = 1) begin
/*insert..*/
set @xml.modify('
insert <leg>{/animal/limbs/limb[1]/text()}</leg>
before (/animal/limbs/limb)[1]
');
/*delete..*/
set @xml.modify('delete (/animal/limbs/limb)[1]');
end
set @xml.modify('
insert <legs>{/animal/limbs/leg}</legs>
before (/animal/limbs)[1]
');
set @xml.modify('delete (/animal/limbs)[1]');
select @xml;
是的,您可以使用DML通过在要重命名的节点处剪切它来重命名元素,将新节点注入到该元素中,然后将剪切的元素粘贴回xml中的该节点。我已经做了一个SQL演示。http://sqlfiddle.com/#!3/dc64d/1 这将会改变
<animal species="Mouse">
<legs>
<leg>Front Right</leg>
<leg>Front Left</leg>
<leg>Back Right</leg>
<leg>Back Left</leg>
</legs>
</animal>
进入
<animal species="Mouse">
<armsandlegs>
<leg>Front Right</leg>
<leg>Front Left</leg>
<leg>Back Right</leg>
<leg>Back Left</leg>
</armsandlegs>
</animal>
SqlFiddle似乎早已破坏了我的解决方案。从记忆中,我在下面粘贴了我的解决方案的基础...
DECLARE @XML2 xml
DECLARE @XML3 xml = '<limbs></limbs>'
DECLARE @XML xml =
'<animal species="Mouse">
<legs>
<leg>Front Right</leg>
<leg>Front Left</leg>
<leg>Back Right</leg>
<leg>Back Left</leg>
</legs>
</animal>'
SET @XML2 = @XML.query('animal/legs/*')
SET @XML.modify('
insert
(sql:variable("@XML3"))
after
(/animal/legs)[1]
')
SET @XML.modify('
delete (/animal/legs[1])
')
SET @XML.modify('
insert
(sql:variable("@XML2"))
as last into
(/animal/limbs)[1]
')
select @XML
<original_record_set><original_record /></original_record_set>
,而用于测试记录的记录集则类似于 <test_record_set><test_record /></ test_record_set >
。SET @output = (SELECT col1, col2
FROM @test_object_result
FOR xml path ( test_record '), root( test_record_set '));
然后:
SET @output = (SELECT col1, col2
FROM @test_object_result
FOR xml path ( original_record'), root( original_record_set '));
然而,由于我多次调用了同一个对象,并且“for xml path”不允许在path('...')
和root('...')
方法中使用变量,因此我不得不想出一种不同的方法。
该函数接受一个xml树并构建一个新树,将根节点替换为@relation_name
的值,并将每个记录的名称替换为@tuple_name
。新树使用原始树的所有属性构建,即使每个记录的属性数量不同也是如此。
例外
显然,这不能处理多个元素级别!我专门构建它来处理单级基于属性的树,如下面的示例所示。我可能会在未来将其扩展到多级混合属性/元素树,但我认为现在解决基本问题的方法已经很明显了,并且将留给读者进行练习。
USE [unit_test];
GO
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[standardize_record_set]') AND type IN ( N'FN', N'IF', N'TF', N'FS', N'FT' ))
DROP FUNCTION [dbo].[standardize_record_set];
GO
SET ANSI_NULLS ON;
GO
SET QUOTED_IDENTIFIER ON;
GO
SET nocount ON;
GO
/*
DECLARE
@relation_name nvarchar(150)= N'standardized_record_set',
@tuple_name nvarchar(150)= N'standardized_record',
@xml xml,
@standardized_result xml;
SET @xml='<Root>
<row id="12" two="now1" three="thr1" four="four1" />
<row id="232" two="now22" three="thr22" />
<row id="233" two="now23" three="thr23" threeextra="extraattrinthree" />
<row id="234" two="now24" three="thr24" fourextra="mealsoin four rwo big mone" />
<row id="235" two="now25" three="thr25" />
</Root>';
execute @standardized_result = [dbo].[standardize_record_set] @relation_name=@relation_name, @tuple_name=@tuple_name, @xml=@xml;
select @standardized_result;
*/
CREATE FUNCTION [dbo].[standardize_record_set] (@relation_name nvarchar(150)= N'record_set',
@tuple_name nvarchar(150)= N'record', @xml xml )
returns XML
AS
BEGIN
DECLARE
@attribute_index int = 1,
@attribute_count int = 0,
@record_set xml = N'<' + @relation_name + ' />',
@record_name nvarchar(50) = @tuple_name,
@builder nvarchar(max),
@record xml,
@next_record xml;
DECLARE @record_table TABLE (
record xml );
INSERT INTO @record_table
SELECT t.c.query('.') AS record
FROM @xml.nodes('/*/*') T(c);
DECLARE record_table_cursor CURSOR FOR
SELECT cast([record] AS xml)
FROM @record_table
OPEN record_table_cursor
FETCH NEXT FROM record_table_cursor INTO @next_record
WHILE @@FETCH_STATUS = 0
BEGIN
SET @attribute_index=1;
SET @attribute_count = @next_record.query('count(/*[1]/@*)').value('.', 'int');
SET @builder = N'<' + @record_name + N' ';
-- build up attribute string
WHILE @attribute_index <= @attribute_count
BEGIN
SET @builder = @builder + @next_record.value('local-name((/*/@*[sql:variable("@attribute_index")])[1])',
'varchar(max)') + '="' + @next_record.value('((/*/@*[sql:variable("@attribute_index")])[1])',
'varchar(max)') + '" ';
SET @attribute_index = @attribute_index + 1
END
-- build record and add to record_set
SET @record = @builder + ' />';
SET @record_set.modify('insert sql:variable("@record") into (/*)[1]');
FETCH NEXT FROM record_table_cursor INTO @next_record
END
CLOSE record_table_cursor;
DEALLOCATE record_table_cursor;
RETURN @record_set;
END;
GO