[英]How to group elements by attribute values using XQuery on SQL Server?
Let's say I have a table in SQL Server which contains the results of a query with an inner join. 假设我在SQL Server中有一个表,其中包含带有内部联接的查询的结果。
The following XQuery: 以下XQuery:
select @code.query
(
'for $s in /root/row
return
<Foo Language="{data($s/@lang)}" Method="{data($s/@method)}" Returns="{data($s/@returnType)}">
<Bar ReferencedBy="{data($s/@callers)}" Static="{data($s/@static)}" />
</Foo>'
)
And its result: 其结果是:
<Foo Language="C#" Method="getFoos" Returns="FooCollection">
<Bar ReferencedBy="Baz" Static="true" />
</Foo>
<Foo Language="C#" Method="getFoos" Returns="FooCollection">
<Bar ReferencedBy="Bar" Static="false" />
</Foo>
What I would like in fact is the following: 我实际上想要的是以下内容:
<Foo Language="C#" Method="getFoos" Returns="FooCollection">
<Bar ReferencedBy="Baz" Static="true" />
<Bar ReferencedBy="Bar" Static="false" />
</Foo>
What's the best way to do this using XQuery in order to avoid resorting to LINQ and a hash table? 为了避免诉诸LINQ和哈希表,使用XQuery做到这一点的最佳方法是什么?
You need to enumerate over all nodes with each language, method and return value before constructing the results 在构造结果之前,需要使用每种语言,方法和返回值枚举所有节点
for $lang in distinct-values(/root/row/@lang)
let $nodes := /root/row[@lang=$lang]
for $method in distinct-values($nodes/@method)
let $nodes := $nodes[@method=$method]
for $return in distinct-values($nodes/@returnType)
let $nodes := $nodes[@returnType=$returnType]
return
<Foo Language="{$lang}"
Method="{$method}"
Returns="{$returnType}">
{
for $bar in $nodes
return
<Bar ReferencedBy="{data($node/@callers)}"
Static="{data($node/@static)}" />
}
</Foo>
I do not use SQL Server myself, so I can't guarantee that this will work, but it is a valid XQuery solution. 我自己没有使用SQL Server,所以不能保证这会起作用,但这是有效的XQuery解决方案。
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