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我的数据库FlowDetailParameter中有一个 XML 类型的列。我的表有一列FlowDetailParameter 和 3 行包含这些数据：

row 1

<ArrayOfFlowDetailParameters xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <FlowDetailParameters>
    <DepartmentId>7</DepartmentId>
    <UserId>6</UserId>
    <Username>4</Username>
    <FullName>کارشناس  معاینه فنی</FullName>
    <ConfirmDateTime>2018-11-01T10:45:29.7371421+03:30</ConfirmDateTime>
    <Comment>اولین IP تاییدی</Comment>
    <Status>Accept</Status>
  </FlowDetailParameters>
  <FlowDetailParameters>
    <DepartmentId>3</DepartmentId>
    <UserId xsi:nil="true" />
    <Username />
    <FullName />
    <ConfirmDateTime xsi:nil="true" />
    <Comment />
    <Status>Pending</Status>
    <AttachmentId />
  </FlowDetailParameters>
</ArrayOfFlowDetailParameters>

row 2

<ArrayOfFlowDetailParameters xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <FlowDetailParameters>
    <DepartmentId>7</DepartmentId>
    <UserId>6</UserId>
    <Username>4</Username>
    <FullName>کارشناس  معاینه فنی</FullName>
    <ConfirmDateTime>2018-11-01T10:45:40.437481+03:30</ConfirmDateTime>
    <Comment>دومین IP تاییدی</Comment>
    <Status>Accept</Status>
  </FlowDetailParameters>
  <FlowDetailParameters>
    <DepartmentId>3</DepartmentId>
    <UserId xsi:nil="true" />
    <Username />
    <FullName />
    <ConfirmDateTime xsi:nil="true" />
    <Comment />
    <Status>Pending</Status>
    <AttachmentId />
  </FlowDetailParameters>
</ArrayOfFlowDetailParameters>


row 3

<ArrayOfFlowDetailParameters xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <FlowDetailParameters>
    <DepartmentId>7</DepartmentId>
    <UserId xsi:nil="true" />
    <Username />
    <FullName />
    <ConfirmDateTime xsi:nil="true" />
    <Comment />
    <Status>Pending</Status>
    <AttachmentId />
  </FlowDetailParameters>
  <FlowDetailParameters>
    <DepartmentId>3</DepartmentId>
    <UserId xsi:nil="true" />
    <Username />
    <FullName />
    <ConfirmDateTime xsi:nil="true" />
    <Comment />
    <Status />
    <AttachmentId />
  </FlowDetailParameters>
</ArrayOfFlowDetailParameters>

我想找到departmentId=3 and status=Pending，所以预期的结果应该返回 2 行。所以这是我的查询：

    select  Requests.*   from Requests

 where    
  ((SELECT count(*)   
 FROM Requests t
    CROSS APPLY t.FlowDetailParameter.nodes ('/ArrayOfFlowDetailParameters/FlowDetailParameters') x(v)
where    x.v.value('(DepartmentId/text())[1]', 'bigint')=3   and  x.v.value('(Status/text())[1]', 'varchar(50)') = 'Pending') >0)

但是我的查询返回所有行（3 行）为什么？

4

1 回答 1

1

首先回答你的问题“为什么？”：

您的子查询不是相关的子查询。没有从外部连接到当前行SELECT。所以 - 假设至少有 1 行满足您的条件 - 这将始终提供count>0.

尽管可以更正您的方法，但我建议使用 XML 方法.exist()并将过滤器提供为XPath/XQuery：

SELECT * 
FROM Requests r
WHERE r.FlowDetailParameter.exist(N'/ArrayOfFlowDetailParameters
                                    /FlowDetailParameters[(DepartmentId/text())[1]=3 
                                                          and (Status/text())[1]="Pending"]')=1;

这将检查任何<FlowDetailParameters>给定条件的存在。

如果要动态引入过滤器，可以使用sql:variable()orsql:column()代替3and"Pending"

DECLARE @depId INT=3;
DECLARE @status VARCHAR(100)='Pending';

SELECT * 
FROM Requests r
WHERE r.FlowDetailParameter.exist(N'/ArrayOfFlowDetailParameters
                                    /FlowDetailParameters[(DepartmentId/text())[1]=sql:variable("@depId")
                                                          and (Status/text())[1]=sql:variable("@status")]')=1
于 2018-11-03T16:08:59.570 回答