使用Xquery计算元素并返回元素名称和值

Question

I have to count how many times of the authors show in a XML file. Lets say,as attached - XML

Frank Manola has appeared 2 times and Tolga Yurek has appeared 1 time.

My desire result is:

Frank Manola , 2
Tolga Yurek, 1

I used this code, but I cannot archive it:

for $a in doc("dblp.xml")/dblp/* let$c := count ($a/author) return ($a/author , $c)

Result become very weird like this: unwanted result

What error in my code? What can I group and sum them up?

Answer 1

You are iterating several times on the same author. Maybe you should use distinct-values when you loop on the authors?

Something like:

for $a in distinct-values(doc("file.xml")//author)
  let $c := count(//author[. = $a])
  return ($a, $c)

Answer 2

In XQuery 3 you can use group by https://www.w3.org/TR/xquery-31/#id-group-by :

for $author in doc("dblp.xml")/dblp/*/author
group by $a := $author
return $a || ': ' || count($author)

https://xqueryfiddle.liberty-development.net/b4GWVe/1