sql查询varchar（max）列以根据其子元素child的值选择一个元素

Question

我正在尝试搜索存储在varchar（max）列中的xml数据。
下面是在varchar列中找到的xml数据字符串之一的示例。在此示例中，我将有一个名为@dsName的sql变量，当其值与@dsName匹配且它从属于or节点时，它将与该节点匹配。 在此之间或直到您到达之间的节点可以不同。

   <business_process>
<ProcessDefinition name="dawns test">
    <StartState name="START" uniqueId="Node3304">
        <Transition name="Node4532" to="Node4532"/>
    </StartState>
    <EndState name="END4694" uniqueId="Node4694"/>
    <User name="Node4532" uniqueId="Node4532">
        <Description>test</Description>
        <Distribution config-type="field" type="CommonQueueDistribution">
            <Priority>0</Priority>
            <AutoCompleteJob>false</AutoCompleteJob>
            <GroupId>Admin</GroupId>
            <UseAttendance>false</UseAttendance>
            <UseShifts>false</UseShifts>
            <NotifyActors>false</NotifyActors>
        </Distribution>
        <DocFinityTask type="DocFinityTask">
            <description>read e-mail and approve or deny</description>
            <help/>
            <required>false</required>
            <redoable>false</redoable>
            <condition/>
            <properties>
                <undoable>true</undoable>
            </properties>
        </DocFinityTask>
        <DocFinityTask type="SimpleFormTask">
            <description>lob lookup</description>
            <help/>
            <required>false</required>
            <redoable>true</redoable>
            <condition/>
            <properties>
                <autoRun>true</autoRun>
                <form>
                    <title>lob</title>
                    <formElement>
                        <type>Combobox</type>
                        <variable>lob</variable>
                        <tooltip>lob lookup</tooltip>
                        <label>lob</label>
                        <required>false</required>
                        <prepopulateValues>
                            <datasourceName>lob lookup</datasourceName>
                        </prepopulateValues>
                        <userEnter>true</userEnter>
                        <dataType>STRING</dataType>
                    </formElement>
                </form>
            </properties>
        </DocFinityTask>
        <Transition name="Node128795" to="Node128795"/>
    </User>
    <Server name="Node128795" uniqueId="Node128795">
        <Description/>
        <Event type="node-enter">
            <Action type="SetProcessInstancePropertyAction" config-type="field">
                <description>Whatever</description>
                <propertyName>source</propertyName>
                <datasourceName>get datasource list</datasourceName>
            </Action>
        </Event>
        <Transition name="Node4694" to="END4694"/>
    </Server>
    <Server name="Node250" uniqueId="Node250">
      <Description />
      <Event type="node-enter">
        <Action type="SetProcessInstancePropertyAction" config-type="field">
          <description>Whatever</description>
          <propertyName>source</propertyName>
          <datasourceName>stump</datasourceName>
        </Action>
      </Event>
      <Transition name="Node4694" to="END4694" />
    </Server>
</ProcessDefinition>
<Layout>
    <annotations/>
    <nodes>
        <node name="START" uniqueId="Node3304" type="startNode" text="START" x="184.5" y="135.5" width="25" height="25"/>
        <node name="END4694" uniqueId="Node4694" type="endNode" text="END4694" x="588.5" y="137.5" width="25" height="25"/>
        <node name="Node4532" uniqueId="Node4532" type="userNode" text="Node4532" info="false" x="296" y="135" width="150" height="50"/>
        <node name="Node128795" uniqueId="Node128795" type="serverNode" text="Node128795" info="false" x="286" y="244" width="150" height="50"/>
    </nodes>
    <edges>
        <edge originNode="Node3304" targetNode="Node4532" text="" sketch="arrow"/>
        <edge originNode="Node4532" targetNode="Node128795" text="" sketch="arrow"/>
        <edge originNode="Node128795" targetNode="Node4694" text="" sketch="arrow"/>
    </edges>
</Layout>

这是我尝试加载到XML数据类型的变量时使用的选择的示例。 varchar（max）列名称为XML

DECLARE @xml XML=
            (SELECT [XML] 
             FROM ProcessModels 
             WHERE [XML] LIKE '%<datasourceName>' + @dsName + '%' 
                    and [status] = 'ACTIVE')

如果我将它加载到表变量中，并且已经使用要搜索的字符串设置了@dsName变量，则SQL select是相同的。

在此示例中，当每个服务器节点和/或用户节点的节点值为“获取数据源列表”时，我想查找它们的名称。 字符串“获取数据源列表”已存在于变量@dsName中。

以下查询将我带到一半。

select sn.value('@name', 'varchar(100)') AS ServerNodes
from @xml.nodes('/business_process/ProcessDefinition/Server')  AS ServerNodes(sn)

现在，我需要弄清楚如何将Server。@ name限制为子节点// datasourceName值等于sql：variable的那些名称。

这工作：

SELECT ServerNode.value('@name','varchar(max)') AS ServerNode
FROM @xml.nodes('/business_process/ProcessDefinition') AS ProcessDefinition(pd)
OUTER APPLY pd.nodes('Server[Event//datasourceName=sql:variable("@searchVariable")]') AS The(ServerNode)
WHERE ServerNode.value('@name','varchar(max)') IS NOT NULL

SELECT UserNode.value('@name','varchar(max)') AS UserNode
FROM @xml.nodes('/business_process/ProcessDefinition') AS ProcessDefinition(pd)
OUTER APPLY pd.nodes('User[DocFinityTask//datasourceName=sql:variable("@searchVariable")]') AS The(UserNode)
WHERE UserNode.value('@name','varchar(max)') IS NOT NULL

Answer 1

您的朋友是sql:variable() ，如果您的搜索值来自表的列，那么还有一个sql:column() 。

根据您的评论，我用varchar类型的XML列模拟了一个表。 SELECT首先将使用CROSS APPLY将其转换为“真实” XML，然后使用.exist()来选择满足您条件的行，最后返回/User/@name值。

如果将lookup-variable更改为“ another”，则会找到其他XML，其他字符串将返回为空。

作为XPath的示例，我给您提供了三个均返回相同查询的查询。 这取决于您的XML ...

DECLARE @tbl TABLE(ID INT IDENTITY, YourXMLAsVarchar VARCHAR(MAX));
INSERT INTO @tbl VALUES 
('<User name="First Node" uniqueId="1332">
    <Task type="Form">
      <properties>
        <form>
          <formElement>
            <populateValues>
              <source>lookup</source>
            </populateValues>
          </formElement>
        </form>
      </properties>
    </Task>
   </User>')
,('<User name="First Node" uniqueId="1332">
    <Task type="Form">
      <properties>
        <form>
          <formElement>
            <populateValues>
              <source>another</source>
            </populateValues>
          </formElement>
        </form>
      </properties>
    </Task>
   </User>');


--Search for "lookup"
DECLARE @SearchingFor VARCHAR(100)='lookup';

--Search with full path
SELECT x.value('(/User/@name)[1]','varchar(max)')
FROM @tbl AS tbl
CROSS APPLY(SELECT CAST(YourXMLAsVarchar AS XML)) AS a(x)
WHERE x.exist('/User/Task/properties/form/formElement/populateValues/source[.=sql:variable("@SearchingFor")]')=1

--shorter, if there is not other "source" element this could be muddled up with...
SELECT x.value('(/User/@name)[1]','varchar(max)')
FROM @tbl AS tbl
CROSS APPLY(SELECT CAST(YourXMLAsVarchar AS XML)) AS a(x)
WHERE x.exist('//source[.=sql:variable("@SearchingFor")]')=1

--even shorter, if your lookup string won't be anywhere else an element's value
SELECT x.value('(/User/@name)[1]','varchar(max)')
FROM @tbl AS tbl
CROSS APPLY(SELECT CAST(YourXMLAsVarchar AS XML)) AS a(x)
WHERE x.exist('//*[.=sql:variable("@SearchingFor")]')=1

Answer 2

因为我的第一个答案已经很拥挤了...

这样，您将从XML中获取用户和服务器的数据。 如果将@searchVariable设置为不存在的datasourceName值，则User数据仍然存在，但是Server数据将为NULL。 试试看！

DECLARE @xml XML=
'<business_process>
  <ProcessDefinition name="dawns test">
    <StartState name="START" uniqueId="Node3304">
      <Transition name="Node4532" to="Node4532" />
    </StartState>
    <EndState name="END4694" uniqueId="Node4694" />
    <User name="Node4532" uniqueId="Node4532">
      <Description>test</Description>
      <Distribution config-type="field" type="CommonQueueDistribution">
        <Priority>0</Priority>
        <AutoCompleteJob>false</AutoCompleteJob>
        <GroupId>Admin</GroupId>
        <UseAttendance>false</UseAttendance>
        <UseShifts>false</UseShifts>
        <NotifyActors>false</NotifyActors>
      </Distribution>
      <DocFinityTask type="DocFinityTask">
        <description>read e-mail and approve or deny</description>
        <help />
        <required>false</required>
        <redoable>false</redoable>
        <condition />
        <properties>
          <undoable>true</undoable>
        </properties>
      </DocFinityTask>
      <DocFinityTask type="SimpleFormTask">
        <description>lob lookup</description>
        <help />
        <required>false</required>
        <redoable>true</redoable>
        <condition />
        <properties>
          <autoRun>true</autoRun>
          <form>
            <title>lob</title>
            <formElement>
              <type>Combobox</type>
              <variable>lob</variable>
              <tooltip>lob lookup</tooltip>
              <label>lob</label>
              <required>false</required>
              <prepopulateValues>
                <datasourceName>lob lookup</datasourceName>
              </prepopulateValues>
              <userEnter>true</userEnter>
              <dataType>STRING</dataType>
            </formElement>
          </form>
        </properties>
      </DocFinityTask>
      <Transition name="Node128795" to="Node128795" />
    </User>
    <Server name="Node128795" uniqueId="Node128795">
      <Description />
      <Event type="node-enter">
        <Action type="SetProcessInstancePropertyAction" config-type="field">
          <description>Whatever</description>
          <propertyName>source</propertyName>
          <datasourceName>get datasource list</datasourceName>
        </Action>
      </Event>
      <Transition name="Node4694" to="END4694" />
    </Server>
  </ProcessDefinition>
  <Layout>
    <annotations />
    <nodes>
      <node name="START" uniqueId="Node3304" type="startNode" text="START" x="184.5" y="135.5" width="25" height="25" />
      <node name="END4694" uniqueId="Node4694" type="endNode" text="END4694" x="588.5" y="137.5" width="25" height="25" />
      <node name="Node4532" uniqueId="Node4532" type="userNode" text="Node4532" info="false" x="296" y="135" width="150" height="50" />
      <node name="Node128795" uniqueId="Node128795" type="serverNode" text="Node128795" info="false" x="286" y="244" width="150" height="50" />
    </nodes>
    <edges>
      <edge originNode="Node3304" targetNode="Node4532" text="" sketch="arrow" />
      <edge originNode="Node4532" targetNode="Node128795" text="" sketch="arrow" />
      <edge originNode="Node128795" targetNode="Node4694" text="" sketch="arrow" />
    </edges>
  </Layout>
</business_process>';

DECLARE @searchVariable VARCHAR(100)='get datasource list';

SELECT ServerNode.value('@name','varchar(max)') AS ServerName
      ,ServerNode.value('@uniqueId','varchar(max)') AS ServerId
      ,pd.value('User[1]/@name','varchar(max)') AS UserName
      ,pd.value('User[1]/@uniqueId','varchar(max)') AS UserId
FROM @xml.nodes('/business_process/ProcessDefinition') AS ProcessDefinition(pd)
OUTER APPLY pd.nodes('Server[Event/Action/datasourceName=sql:variable("@searchVariable")]') AS The(ServerNode);

Answer 3

另一个选择。 它不使用XML.exist而是直接查找具有<source>元素和lookup变量的User元素。 然后，将路径反向返回到祖先User并选择name属性。

DECLARE @xml XML=
'<User name="First Node" uniqueId="1332">
    <Task type="Form">
        <properties>
            <form>
                <formElement>
                    <populateValues>
                        <source>lookup</source>
                    </populateValues>
                </formElement>
            </form>
        </properties>
    </Task>
</User>';

DECLARE @lookup NVARCHAR(128)='lookup';

SELECT
    n.v.value('../../../../../../@name','NVARCHAR(128)') AS name
FROM
    @xml.nodes('//User/Task/properties/form/formElement/populateValues/source[.=sql:variable("@lookup")]') AS n(v);

显然，不完全支持XPath轴（至少在SQL Server 2012中不支持）。 如果不是../../../../../../@name ，则可以编写更简单的ancestor::User/@name 。