mysql - 为什么它只在 JSONiq 中返回最后一个元素？

Question

我的 json 和查询的图像

json代码

{
    "reading_list": {
        "book": {
            "name": "Fifty shades of grey",
            "author": "E.L James",
            "date": "March 2015",
            "comment": "did not like it very much"
        },
        "book": {
            "name": "The grass is singing",
            "author": "Doris Lessing",
            "date": "April 2015",
            "comment": "enjoyed it quite a bit"
        },
        "book": {
            "name": "A short history of nearly everything",
            "author": "Bill Bryson",
            "date": "June 2015",
            "comment": "very informative"
        },
        "book": {
            "name": "JSON in 24 hours",
            "author": "Peter Settler",
            "date": "in the year",
            "comment": "read for work"
        },
        "book": {
            "name": "Miss Smilla's feeling for snow",
            "author": "Peter Hoeg's",
            "date": "in the year",
            "comment": "read for entertainment"
        }
    }
}

查询代码：

for $x in reading_list
return $x("book")/name

正如您从链接中看到的那样，我希望得到所有的书名，但我只得到：

Miss Smilla's feeling for snow.
The output should be like this:
Fifty shades of grey
A short history of nearly everything
The grass is singing
JSON in 24 hours
Miss Smilla's feeling for snow

出了什么问题？..请帮忙

Answer 1

在 JSONiq 数据模型 (JDM) 中，不允许重复键（例如您的示例中的 book）。似乎此实现不会引发错误，而是使用该密钥的最后一对。

在原始 JSON RFC中，这个约束是一个应该。您可以通过将阅读列表建模为书籍数组来增加互操作性。