常用的XM查询语言: XQUERY ●例12.3查询每本书的作者人数以及每位作者的名字,语句为: Results> FOR$ book IN//book//指定变量$book的取值范围是结点<book> LET authors Sbook/author //把变量$ authors赋值为$book的子结点< author> RETURN <book author Count=( count(authors)j> FOR Author In Authors RETURN Author> Author/last/textoauthor> </book> S/ results.常用的XML查询语言：XQUERY ⚫ 例12.3 查询每本书的作者人数以及每位作者的名字，语句为： <results> { FOR $book IN //book //指定变量$book的取值范围是结点<book> LET $authors := $book/author //把变量$authors赋值为$book的子结点<author> RETURN <book authorCount={ count($authors) }> { FOR $author IN $authors RETURN <author>{ $author/last/text() }</author> } </book> } </results>