SQL Server在条件列中的xml列中返回null

Question

您可以看到，我的XML Sql列中有此内容：

<LabelRequestInputParameters xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Count>100</Count>
  <ConfirmedCountByMunicipality xsi:nil="true" />
  <ConfirmedCountByProvincialGovernment xsi:nil="true" />
  <ConfirmedCountBySymfaExpert xsi:nil="true" />
  <TypeOfLabelDelivery>Post</TypeOfLabelDelivery>
  <TypeOfLabel>Public</TypeOfLabel>
  <NextState>Municipality</NextState>
</LabelRequestInputParameters>

我想选择count = 100的所有节点

    declare @a nvarchar(max)
  set @a='100'
  select InputParameter.value(N'(/LabelRequestInputParameters/Count[@Count=(sql:variable("@a"))])[1]', 'Bigint') from Requests  

但是当我运行此查询时，所有值都为null：

Answer 1

假设您的XML结构相似并且只有元素中的值不同，您可以使用以下XQuery提取它：

DECLARE @a INT = 100
DECLARE @Tbl TABLE (XmlCol XML) 
INSERT INTO @Tbl
VALUES (
 '<LabelRequestInputParameters xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Count>100</Count>
  <ConfirmedCountByMunicipality xsi:nil="true" />
  <ConfirmedCountByProvincialGovernment xsi:nil="true" />
  <ConfirmedCountBySymfaExpert xsi:nil="true" />
  <TypeOfLabelDelivery>Post</TypeOfLabelDelivery>
  <TypeOfLabel>Public</TypeOfLabel>
  <NextState>Municipality</NextState>
</LabelRequestInputParameters>'
) ,

(
 '<LabelRequestInputParameters xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Count>100</Count>
  <ConfirmedCountByMunicipality xsi:nil="true" />
  <ConfirmedCountByProvincialGovernment xsi:nil="true" />
  <ConfirmedCountBySymfaExpert xsi:nil="true" />
  <TypeOfLabelDelivery>Post</TypeOfLabelDelivery>
  <TypeOfLabel>Public</TypeOfLabel>
  <NextState>Municipality</NextState>
</LabelRequestInputParameters>'
),

(
 '<LabelRequestInputParameters xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Count>150</Count>
  <ConfirmedCountByMunicipality xsi:nil="true" />
  <ConfirmedCountByProvincialGovernment xsi:nil="true" />
  <ConfirmedCountBySymfaExpert xsi:nil="true" />
  <TypeOfLabelDelivery>Post</TypeOfLabelDelivery>
  <TypeOfLabel>Public</TypeOfLabel>
  <NextState>Municipality</NextState>
</LabelRequestInputParameters>'
),
(
 '<LabelRequestInputParameters xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Count>150</Count>
  <ConfirmedCountByMunicipality xsi:nil="true" />
  <ConfirmedCountByProvincialGovernment xsi:nil="true" />
  <ConfirmedCountBySymfaExpert xsi:nil="true" />
  <TypeOfLabelDelivery>Post</TypeOfLabelDelivery>
  <TypeOfLabel>Public</TypeOfLabel>
  <NextState>Municipality</NextState>
</LabelRequestInputParameters>'
)

SELECT  q.Cnt
FROM @Tbl
    CROSS APPLY XmlCol.nodes ('/LabelRequestInputParameters/Count') l(x)
    CROSS APPLY 
        (
        VALUES (l.x.value ('.','varchar(1000)'))
        ) Q(Cnt)

WHERE q.Cnt = @a

Answer 2

如果我正确理解这一点，则表中有很多行，每一行都保留一个XML，每一行都具有给定的结构。因此<Count>每行将只存在一次。是吗？

如果是这样，请尝试以下操作：

DECLARE @SomeTable TABLE(YourXML XML);
INSERT INTO @SomeTable VALUES
(N'<LabelRequestInputParameters>
  <Count>100</Count>
  <test>test 100</test>
</LabelRequestInputParameters>')
,(N'<LabelRequestInputParameters>
  <Count>200</Count>
  <test>test 200</test>
</LabelRequestInputParameters>');

SELECT *
FROM @SomeTable
WHERE YourXML.value('(/LabelRequestInputParameters/Count/text())[1]','int') = 100;

更新：您自己的代码中的一些单词

您的代码：

.value(N'(/LabelRequestInputParameters/Count[@Count=(sql:variable("@a"))])[1]', 'Bigint')

这将深入到<Count>，并将过滤出现此名称的属性并将其与您引入的变量进行比较。如果有这样的事情，这可能会起作用

<Count Count="100">100</Count>

Answer 3

   SELECT InputParameter.value(N'(/LabelRequestInputParameters/Count)[1]','bigint')
    FROM Requests
    WHERE InputParameter.exist(N'/LabelRequestInputParameters/Count[.="100"]')=1
    GO