XQuery：需要过滤提示

Question

给定像这样的 XML 文件记录，

<ADR-NSBG>
    <timeline timestamp="2011-06-09T00:15:00">
        <datum datum="SGC_at_bsNo-14___SignalingNetworkConnection_at_netId-4___Sip_at_networkRole-2">
            <sbgSipTotalIncSipRequests>4314320</sbgSipTotalIncSipRequests>
            <sbgSipTotalIncSipResponses>9040481</sbgSipTotalIncSipResponses>
            <sbgSipTotalIncFailureResponses>2321242</sbgSipTotalIncFailureResponses>
            <sbgSipTotalOutSipRequests>9136608</sbgSipTotalOutSipRequests>
            <sbgSipTotalOutSipResponses>4643002</sbgSipTotalOutSipResponses>
            <sbgSipTotalOutFailureResponses>1027420</sbgSipTotalOutFailureResponses>
            <sbgSipIncommingProvisionalResponses>3433875</sbgSipIncommingProvisionalResponses>
            <sbgSipOutgoingProvisionalResponses>1845750</sbgSipOutgoingProvisionalResponses>
        </datum>
        <datum datum="SGC_at_bsNo-13___SignalingNetworkConnection_at_netId-4___Sip_at_networkRole-2">
            <sbgSipTotalIncSipRequests>4799739</sbgSipTotalIncSipRequests>
            <sbgSipTotalIncSipResponses>9335965</sbgSipTotalIncSipResponses>
            <sbgSipTotalIncFailureResponses>2415690</sbgSipTotalIncFailureResponses>
            <sbgSipTotalOutSipRequests>9474295</sbgSipTotalOutSipRequests>
            <sbgSipTotalOutSipResponses>5291708</sbgSipTotalOutSipResponses>
            <sbgSipTotalOutFailureResponses>1149950</sbgSipTotalOutFailureResponses>
            <sbgSipIncommingProvisionalResponses>3516298</sbgSipIncommingProvisionalResponses>
            <sbgSipOutgoingProvisionalResponses>2190601</sbgSipOutgoingProvisionalResponses>
        </datum>
    </timeline>
</ADR-NSBG>

我想做的是获取 datum 元素的子元素的值。

所以，我编写了以下查询：

for         $i in collection("/db/_DEMO/ADR-NSBG/sipTransactTM/2011/06/09")
let         $TIME_FROM := "2011-06-09T00:15:00"
let         $TIME_TO := "2011-06-09T00:45:00"
let         $DATUM := "SGC_at_bsNo-13___SignalingNetworkConnection_at_netId-4___Sip_at_networkRole-2"
where       ( $i/ADR-NSBG/timeline/@timestamp/string(.) >= $TIME_FROM and
            $i/ADR-NSBG/timeline/@timestamp/string(.) <= $TIME_TO) and
            ( $i/ADR-NSBG/timeline/datum/@datum/string(.) = $DATUM )
order by    $i/ADR-NSBG/timeline/@timestamp/string(.)
return      $i/ADR-NSBG/timeline/datum

但是，问题是我无法在两个“数据”节点之间进行选择。 查询的结果是：

<datum datum="SGC_at_bsNo-14___SignalingNetworkConnection_at_netId-4___Sip_at_networkRole-2">
    <sbgSipTotalIncSipRequests>4314320</sbgSipTotalIncSipRequests>
    <sbgSipTotalIncSipResponses>9040481</sbgSipTotalIncSipResponses>
    <sbgSipTotalIncFailureResponses>2321242</sbgSipTotalIncFailureResponses>
    <sbgSipTotalOutSipRequests>9136608</sbgSipTotalOutSipRequests>
    <sbgSipTotalOutSipResponses>4643002</sbgSipTotalOutSipResponses>
    <sbgSipTotalOutFailureResponses>1027420</sbgSipTotalOutFailureResponses>
    <sbgSipIncommingProvisionalResponses>3433875</sbgSipIncommingProvisionalResponses>
    <sbgSipOutgoingProvisionalResponses>1845750</sbgSipOutgoingProvisionalResponses>
</datum>
<datum datum="SGC_at_bsNo-13___SignalingNetworkConnection_at_netId-4___Sip_at_networkRole-2">
    <sbgSipTotalIncSipRequests>4799739</sbgSipTotalIncSipRequests>
    <sbgSipTotalIncSipResponses>9335965</sbgSipTotalIncSipResponses>
    <sbgSipTotalIncFailureResponses>2415690</sbgSipTotalIncFailureResponses>
    <sbgSipTotalOutSipRequests>9474295</sbgSipTotalOutSipRequests>
    <sbgSipTotalOutSipResponses>5291708</sbgSipTotalOutSipResponses>
    <sbgSipTotalOutFailureResponses>1149950</sbgSipTotalOutFailureResponses>
    <sbgSipIncommingProvisionalResponses>3516298</sbgSipIncommingProvisionalResponses>
    <sbgSipOutgoingProvisionalResponses>2190601</sbgSipOutgoingProvisionalResponses>
</datum>

我想问你的是：为什么语句 ( $i/ADR-NSBG/timeline/datum/@datum/string(.) = $DATUM ) 会这样做不工作？

Answer 1

在 where 子句中，您使用 datum 元素过滤 for 子句的 $i 元素。您没有过滤数据元素。

该表达式：

( $i/ADR-NSBG/timeline/datum/@datum/string(.) = $DATUM )

解析为：

(
 "SGC_at_bsNo-14___SignalingNetworkConnection_at_netId-4___Sip_at_networkRole-2",
 "SGC_at_bsNo-13___SignalingNetworkConnection_at_netId-4___Sip_at_networkRole-2"
) =
 "SGC_at_bsNo-13___SignalingNetworkConnection_at_netId-4___Sip_at_networkRole-2"

这是正确的。因此，选择了$i元素。之后，return 子句中的表达式会选择包含的时间轴元素的两个子元素：

$i/ADR-NSBG/timeline/datum

如何过滤数据元素

如果您只想选择具有特定字符串的数据，则需要过滤返回子句：

$i/ADR-NSBG/timeline/datum[@datum eq $DATUM]