[英]XQuery: How to get a specific value out of a tag?
Suppose we have this xml:假设我们有这个 xml:
<question>
<test id="1">
<tag k="a" v="1"/>
<tag k="a" v="2"/>
<tag k="b" v="3"/>
</test>
<test id="2">
<tag k="a" v="1"/>
<tag k="a" v="4"/>
<tag k="b" v="5"/>
</test>
<test id="3">
<tag k="a" v="2"/>
<tag k="a" v="6"/>
<tag k="b" v="7"/>
</test>
</question>
I would like to return all values v of test, if k = "a" AND v = "1", like this:如果 k = "a" AND v = "1",我想返回测试的所有值 v,如下所示:
v="3"
v="5"
So far my approach:到目前为止我的方法:
for $i in //test
where ($i/tag[@k = 'a' and @v = '1'])
return $i/tag/@v
But this is not correct because thats the return:但这是不正确的,因为那是回报:
v="1"
v="2"
v="3"
v="1"
v="4"
v="5"
Thank you for your help:)谢谢您的帮助:)
You are probably looking for something like您可能正在寻找类似的东西
for $i in //test
where ($i/tag[@k = 'a'][@v="1"])
return $i/tag[@k="b"]/@v
Your criteria for selection was not exactly clear, but this returns what you expected:您的选择标准并不十分清楚,但这会返回您所期望的:
for $i in //test
where $i/tag[@k = 'a' and @v = '1']
return $i/tag[not(@k = 'a' or @v = '1')]/@v
You could simplify and do this in a single XPath expression:您可以简化并在单个 XPath 表达式中执行此操作:
//test/tag[@k = 'a' and @v = '1']/tag[not(@k = 'a' or @v = '1')]/@v
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