Xquery 查询以从关联标头中检索值以获取详细信息答案

【问题标题】：Xquery query to retreive values from associated header for detailXquery 查询以从关联标头中检索值以获取详细信息
【发布时间】：2021-10-30 23:08:16
【问题描述】：

我有可以从中检索值的 XML，但我使用的解决方案对不同的结构化 XML 工作正常。

XML

<del:DeliverMeterReading xmlns:del="http://schemas.fortum.com/amm/delivermeterreading">
  <del:Header>
    <del:MessageId>x</del:MessageId>
    <del:MessageType>y</del:MessageType>
    <del:MessageCreatedTimestamp>2021-10-27T22:10:25.362+00:00</del:MessageCreatedTimestamp>
    <del:MessageReceivedTimestamp>2021-10-27T22:10:31+00:00</del:MessageReceivedTimestamp>
    <del:DispatchId>z</del:DispatchId>
  </del:Header>
  <del:DataRows>
    <del:Data>
      <del:TaskTypeId>0</del:TaskTypeId>
      <del:TaskId>1</del:TaskId>
      <del:DeliverySiteEANCode>1</del:DeliverySiteEANCode>
      <del:SvkCode>901</del:SvkCode>
      <del:MeterId>-1</del:MeterId>
      <del:DeliveryFormat>E</del:DeliveryFormat>
      <del:ReadingStartDate>2021-08-28T00:00:00.000+00:00</del:ReadingStartDate>
      <del:ReadingEndDate>2021-08-28T23:00:00.000+00:00</del:ReadingEndDate>
      <del:Resolution>PT1H</del:Resolution>
      <del:SpSla />
      <del:RecordPosition>1</del:RecordPosition>
      <del:Values>
        <del:Value position="1" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T00:00:00.000+00:00" requestedReadingDate="2021-08-28T00:00:00.000+00:00" reading="96542.26" status="51" meterReadingId="1459846141" />
        <del:Value position="2" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T01:00:00.000+00:00" requestedReadingDate="2021-08-28T01:00:00.000+00:00" reading="96542.54" status="51" meterReadingId="1459846142" />
        <del:Value position="3" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T02:00:00.000+00:00" requestedReadingDate="2021-08-28T02:00:00.000+00:00" reading="96542.79" status="51" meterReadingId="1459846143" />
        <del:Value position="4" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T03:00:00.000+00:00" requestedReadingDate="2021-08-28T03:00:00.000+00:00" reading="96543.06" status="51" meterReadingId="1459846144" />
        <del:Value position="5" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T04:00:00.000+00:00" requestedReadingDate="2021-08-28T04:00:00.000+00:00" reading="96543.31" status="51" meterReadingId="1459846145" />
        <del:Value position="6" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T05:00:00.000+00:00" requestedReadingDate="2021-08-28T05:00:00.000+00:00" reading="96543.58" status="51" meterReadingId="1459846146" />
        <del:Value position="7" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T06:00:00.000+00:00" requestedReadingDate="2021-08-28T06:00:00.000+00:00" reading="96543.99" status="51" meterReadingId="1459846147" />
        <del:Value position="8" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T07:00:00.000+00:00" requestedReadingDate="2021-08-28T07:00:00.000+00:00" reading="96544.43" status="51" meterReadingId="1459846148" />
        <del:Value position="9" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T08:00:00.000+00:00" requestedReadingDate="2021-08-28T08:00:00.000+00:00" reading="96544.89" status="51" meterReadingId="1459846149" />
        <del:Value position="10" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T09:00:00.000+00:00" requestedReadingDate="2021-08-28T09:00:00.000+00:00" reading="96545.29" status="51" meterReadingId="1459846150" />
        <del:Value position="11" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T10:00:00.000+00:00" requestedReadingDate="2021-08-28T10:00:00.000+00:00" reading="96546.02" status="51" meterReadingId="1459846151" />
        <del:Value position="12" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T11:00:00.000+00:00" requestedReadingDate="2021-08-28T11:00:00.000+00:00" reading="96547.37" status="51" meterReadingId="1459846152" />
        <del:Value position="13" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T12:00:00.000+00:00" requestedReadingDate="2021-08-28T12:00:00.000+00:00" reading="96548.04" status="51" meterReadingId="1459846153" />
        <del:Value position="14" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T13:00:00.000+00:00" requestedReadingDate="2021-08-28T13:00:00.000+00:00" reading="96549.92" status="51" meterReadingId="1459846154" />
        <del:Value position="15" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T14:00:00.000+00:00" requestedReadingDate="2021-08-28T14:00:00.000+00:00" reading="96550.69" status="51" meterReadingId="1459846155" />
        <del:Value position="16" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T15:00:00.000+00:00" requestedReadingDate="2021-08-28T15:00:00.000+00:00" reading="96551.69" status="51" meterReadingId="1459846156" />
        <del:Value position="17" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T16:00:00.000+00:00" requestedReadingDate="2021-08-28T16:00:00.000+00:00" reading="96553.68" status="51" meterReadingId="1459846157" />
        <del:Value position="18" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T17:00:00.000+00:00" requestedReadingDate="2021-08-28T17:00:00.000+00:00" reading="96555.07" status="51" meterReadingId="1459846158" />
        <del:Value position="19" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T18:00:00.000+00:00" requestedReadingDate="2021-08-28T18:00:00.000+00:00" reading="96557.56" status="51" meterReadingId="1459846159" />
        <del:Value position="20" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T19:00:00.000+00:00" requestedReadingDate="2021-08-28T19:00:00.000+00:00" reading="96558.36" status="51" meterReadingId="1459846160" />
        <del:Value position="21" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T20:00:00.000+00:00" requestedReadingDate="2021-08-28T20:00:00.000+00:00" reading="96559.01" status="51" meterReadingId="1459846161" />
        <del:Value position="22" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T21:00:00.000+00:00" requestedReadingDate="2021-08-28T21:00:00.000+00:00" reading="96559.82" status="51" meterReadingId="1459846162" />
        <del:Value position="23" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T22:00:00.000+00:00" requestedReadingDate="2021-08-28T22:00:00.000+00:00" reading="96560.44" status="51" meterReadingId="1459846163" />
        <del:Value position="24" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T23:00:00.000+00:00" requestedReadingDate="2021-08-28T23:00:00.000+00:00" reading="96560.83" status="51" meterReadingId="1459846164" />
      </del:Values>
    </del:Data>
    <del:Data>
      <del:TaskTypeId>0</del:TaskTypeId>
      <del:TaskId>2</del:TaskId>
      <del:DeliverySiteEANCode>2</del:DeliverySiteEANCode>
      <del:SvkCode>901</del:SvkCode>
      <del:MeterId>-1</del:MeterId>
      <del:DeliveryFormat>E</del:DeliveryFormat>
      <del:ReadingStartDate>2021-08-28T00:00:00.000+00:00</del:ReadingStartDate>
      <del:ReadingEndDate>2021-08-28T23:00:00.000+00:00</del:ReadingEndDate>
      <del:Resolution>PT1H</del:Resolution>
      <del:SpSla />
      <del:RecordPosition>2</del:RecordPosition>
      <del:Values>
        <del:Value position="1" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T00:00:00.000+00:00" requestedReadingDate="2021-08-28T00:00:00.000+00:00" reading="126748.93" status="50" meterReadingId="1459846165" />
        <del:Value position="2" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T01:00:00.000+00:00" requestedReadingDate="2021-08-28T01:00:00.000+00:00" reading="126749.71" status="50" meterReadingId="1459846166" />
        <del:Value position="3" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T02:00:00.000+00:00" requestedReadingDate="2021-08-28T02:00:00.000+00:00" reading="126750.49" status="50" meterReadingId="1459846167" />
        <del:Value position="4" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T03:00:00.000+00:00" requestedReadingDate="2021-08-28T03:00:00.000+00:00" reading="126751.27" status="50" meterReadingId="1459846168" />
        <del:Value position="5" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T04:00:00.000+00:00" requestedReadingDate="2021-08-28T04:00:00.000+00:00" reading="126752.06" status="50" meterReadingId="1459846169" />
        <del:Value position="6" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T05:00:00.000+00:00" requestedReadingDate="2021-08-28T05:00:00.000+00:00" reading="126752.84" status="50" meterReadingId="1459846170" />
        <del:Value position="7" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T06:00:00.000+00:00" requestedReadingDate="2021-08-28T06:00:00.000+00:00" reading="126753.62" status="50" meterReadingId="1459846171" />
        <del:Value position="8" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T07:00:00.000+00:00" requestedReadingDate="2021-08-28T07:00:00.000+00:00" reading="126754.4" status="50" meterReadingId="1459846172" />
        <del:Value position="9" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T08:00:00.000+00:00" requestedReadingDate="2021-08-28T08:00:00.000+00:00" reading="126755.18" status="50" meterReadingId="1459846173" />
        <del:Value position="10" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T09:00:00.000+00:00" requestedReadingDate="2021-08-28T09:00:00.000+00:00" reading="126755.96" status="50" meterReadingId="1459846174" />
        <del:Value position="11" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T10:00:00.000+00:00" requestedReadingDate="2021-08-28T10:00:00.000+00:00" reading="126756.74" status="50" meterReadingId="1459846175" />
        <del:Value position="12" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T11:00:00.000+00:00" requestedReadingDate="2021-08-28T11:00:00.000+00:00" reading="126757.52" status="50" meterReadingId="1459846176" />
        <del:Value position="13" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T12:00:00.000+00:00" requestedReadingDate="2021-08-28T12:00:00.000+00:00" reading="126758.3" status="50" meterReadingId="1459846177" />
        <del:Value position="14" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T13:00:00.000+00:00" requestedReadingDate="2021-08-28T13:00:00.000+00:00" reading="126759.08" status="50" meterReadingId="1459846178" />
        <del:Value position="15" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T14:00:00.000+00:00" requestedReadingDate="2021-08-28T14:00:00.000+00:00" reading="126759.86" status="50" meterReadingId="1459846179" />
        <del:Value position="16" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T15:00:00.000+00:00" requestedReadingDate="2021-08-28T15:00:00.000+00:00" reading="126760.64" status="50" meterReadingId="1459846180" />
        <del:Value position="17" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T16:00:00.000+00:00" requestedReadingDate="2021-08-28T16:00:00.000+00:00" reading="126761.42" status="50" meterReadingId="1459846181" />
        <del:Value position="18" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T17:00:00.000+00:00" requestedReadingDate="2021-08-28T17:00:00.000+00:00" reading="126762.2" status="50" meterReadingId="1459846182" />
        <del:Value position="19" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T18:00:00.000+00:00" requestedReadingDate="2021-08-28T18:00:00.000+00:00" reading="126762.98" status="50" meterReadingId="1459846183" />
        <del:Value position="20" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T19:00:00.000+00:00" requestedReadingDate="2021-08-28T19:00:00.000+00:00" reading="126763.76" status="50" meterReadingId="1459846184" />
        <del:Value position="21" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T20:00:00.000+00:00" requestedReadingDate="2021-08-28T20:00:00.000+00:00" reading="126764.54" status="50" meterReadingId="1459846185" />
        <del:Value position="22" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T21:00:00.000+00:00" requestedReadingDate="2021-08-28T21:00:00.000+00:00" reading="126765.32" status="50" meterReadingId="1459846186" />
        <del:Value position="23" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T22:00:00.000+00:00" requestedReadingDate="2021-08-28T22:00:00.000+00:00" reading="126766.1" status="50" meterReadingId="1459846187" />
        <del:Value position="24" registrationDate="2021-10-27T22:01:51.000+00:00" readingDate="2021-08-28T23:00:00.000+00:00" requestedReadingDate="2021-08-28T23:00:00.000+00:00" reading="126766.88" status="50" meterReadingId="1459846188" />
      </del:Values>
    </del:Data>
  </del:DataRows>
</del:DeliverMeterReading>

查询

WITH XMLNAMESPACES(DEFAULT N'http://schemas.fortum.com/amm/delivermeterreading')
SELECT DISTINCT
    t.file_name, t.file_created_time received_timestamp
    ,h.value(N'(Header/MessageCreatedTimestamp)[1]', 'varchar(40)') as created_timestamp
    ,h.value(N'(Header/DispatchId)[1]', 'varchar(40)') as dispatch_id
    ,d.value(N'(DeliverySiteEANCode)[1]', 'varchar(40)') ean
    --,d.value(N'(ReadingStartDate)[1]', 'varchar(40)') ReadingStartDate
    --,d.value(N'(TaskId)[1]', 'varchar(40)') taskid
    --,d.value(N'(RecordPosition)[1]', 'varchar(40)') RecordPosition
    ,v.value(N'@position','varchar(35)') position
    ,v.value(N'@reading','varchar(35)') reading
    ,v.value(N'@status','varchar(35)') status
FROM
    load.t t
OUTER APPLY
    t.xml_data.nodes('/DeliverMeterReading') AS h(h)
OUTER APPLY
    t.xml_data.nodes('/DeliverMeterReading/DataRows/Data') AS delsite(d)
OUTER APPLY
    d.nodes('/Values') AS readings(v)

读数应用的目的是通过获取与每个 del:DeliverySiteEANCode 关联的值来尝试并执行一些相关应用。我只需要这样做，因为否则我会得到一些笛卡尔积或其他东西，因此它无法将我检索到的值与这些值所属的 del:DeliverySiteEANCode 匹配。如果有某种方法可以在 XML 层次结构中向上遍历以检索值，那就太好了。这样我就可以从最细粒度的级别开始，并附加该详细信息的标题信息。因此，在这种情况下，当检索 Value position = "1" 时，我还连接了 del:DeliverySiteEANCode。

使用 SQL Server 2019。

【问题讨论】：

提问时，您需要提供minimal reproducible example： (1) DDL 和样本数据填充，即 CREATE 表和 INSERT T-SQL 语句。 (2) 你需要做什么，即逻辑和你的代码尝试在 T-SQL 中实现它。 (3) 期望的输出，基于上述#1 中的样本数据。 (4) 您的 SQL Server 版本 (SELECT @@version;)。

标签： sql-server xquery-sql

【解决方案1】：

你有两个错误：

/Values 你从根开始。如果您取消/，它将从当前的Data 节点开始
您不会再次下降到Value 节点

所以你应该有

OUTER APPLY
    d.nodes('Values/Value') AS readings(v)

这里还有其他效率：

将/text() 添加到每个.value 性能更高（不要为@ 属性执行此操作）
第一个.nodes应该直接引用Header节点
DISTINCT 有性能成本。不要只是在查询中扔掉DISTINCT 以消除重复项，首先要考虑他们是如何到达那里的。

WITH XMLNAMESPACES(DEFAULT N'http://schemas.fortum.com/amm/delivermeterreading')
SELECT
    h.value(N'(MessageCreatedTimestamp/text())[1]', 'varchar(40)') as created_timestamp
    ,h.value(N'(DispatchId/text())[1]', 'varchar(40)') as dispatch_id
    ,d.value(N'(DeliverySiteEANCode/text())[1]', 'varchar(40)') ean
    --,d.value(N'(ReadingStartDate/text())[1]', 'varchar(40)') ReadingStartDate
    --,d.value(N'(TaskId/text())[1]', 'varchar(40)') taskid
    --,d.value(N'(RecordPosition/text())[1]', 'varchar(40)') RecordPosition
    ,v.value(N'@position','varchar(35)') position
    ,v.value(N'@reading','varchar(35)') reading
    ,v.value(N'@status','varchar(35)') status
FROM
    dbo.t t
OUTER APPLY
    t.xml_data.nodes('/DeliverMeterReading/Header') AS h(h)
OUTER APPLY
    t.xml_data.nodes('/DeliverMeterReading/DataRows/Data') AS delsite(d)
OUTER APPLY
    delsite.d.nodes('Values/Value') AS readings(v)

db<>fiddle

【讨论】：

谢谢，它成功了。你能推荐任何学习xquery的好资源吗？与普通的关系 sql 相比，MS 的官方文档并不容易进入。例如，我在其他问题中看到有时会使用 text() ，但不清楚为什么会使用它。附言我同意我不应该添加 DISTINCT，而是试图理解为什么我得到重复的行。
text() 用于获取节点的内部文本。它的性能更高，因为否则您将有效地转换整个节点，例如string(SomeNode)，这很慢。属性不需要它，因为无论如何它们都是字符串。我同意文档可以改进，我在其他地方没有发现更好的。