Xquery group by on 2 tags

问题

Below is the XML part of my data.

<A>
 <a><Type>Fruit</Type><Name>Banana</Name></a>
 <a><Type>Fruit</Type><Name>Orange</Name></a>
 <a><Type>Fruit</Type><Name>Apple</Name></a>
 <a><Type>Fruit</Type><Name>Lemon</Name></a>
 <a><Type>Cars</Type><Name>Toyota</Name></a>
 <a><Type>Cars</Type><Name>Lamborghini</Name></a>
 <a><Type>Cars</Type><Name>Renault</Name></a>
</A>

Out put as -

<a>Fruits-Banana,Orange,Apple,Lemon</a>
<a>Cars-Toyota,Lamborghini,Renault</a>

I tried to get the required output by all in vain. I tried 'group by` clause too, but getting errors.

any help?

回答1:

let $x:=
<A>
  <a><Type>Fruit</Type><Name>Banana</Name></a>
  <a><Type>Fruit</Type><Name>Orange</Name></a>
  <a><Type>Fruit</Type><Name>Apple</Name></a>
  <a><Type>Fruit</Type><Name>Lemon</Name></a>
  <a><Type>Cars</Type><Name>Toyota</Name></a>
  <a><Type>Cars</Type><Name>Lamborghini</Name></a>
  <a><Type>Cars</Type><Name>Renault</Name></a>
</A>

  for $z in distinct-values($x//a/Type)
    let $c := $x//a[Type=$z]/Name
    return
       <a>{concat($z, "-", string-join($c, ","))}</a>

First for is taking the distinct values of the tag Type, then for each distinct value of this, the respective values of all the Name tags are derived.

Then using the concat function I have concatenated the Type text with the string generated by string-join, used to add/append the Name and , (comma).

HTH :)

来源：https://stackoverflow.com/questions/21284293/xquery-group-by-on-2-tags