在 SPARQL 屏蔽结果中排序

Question

我在 Sparql 中有一个很长的查询，我想按数值字段"情绪"对结果进行排序 如果我在 SELECT 和 GROUPBY 中包含该字段，一切正常，否则会崩溃。但我想呈现查询而不像在 SQL 查询中那样显示字段"情绪"。这在SPARQL中可能吗？

查询为：

SELECT  ?Sentiment ?Restaurant ?Name ?Address ?Score ?City ?State (SAMPLE(?photo) as ?image) SAMPLE(?Text) as ?text) (SAMPLE(?Review) as ?review) (SAMPLE(?TStyle) as ?style) (SAMPLE(?TAmbiance) as   ?ambient) (SAMPLE(?TService) as ?service)
where { ?Restaurant :hasName ?Name;
:Dish ?Dish;
:Score ?Score;
:hasAddress ?Address;
:photo ?photo;
:HasReview ?Review;
:Parking ?Parking;
:CreditCard ?CreditCard;
:Delivery ?Delivery;
:Kids ?Kids;
:hasTopic ?o;
:Sentiment ?Sentiment.
?Address :hasCity ?City;
:hasState ?State;
:Lat ?Lat;
:Long ?Long.
?Review :Text ?Text.
BIND (exists{?Restaurant :hasTopic :style} AS ?TStyle).              
BIND (exists{?Restaurant :hasTopic :ambiance} AS ?TAmbiance).
BIND (exists{?Restaurant :hasTopic :service} AS ?TService).
FILTER(contains(str(?Text), "sushi"))
} GROUP BY ?Restaurant ?Name ?Address ?Score ?City ?State ?Sentiment
ORDER BY DESC((?Sentiment))

如何在不显示字段"情绪"本身或总体上改进查询的情况下形成查询并对结果进行排序？

谢谢。

Answer 1

感谢您的报告。如果未投影变量，ORDER BY 可能会出错，这是一个已知的 AllegroGraph 问题 (bug25806(，将在即将发布的 7.0 版本中修复。

Answer 2

虽然我对 SPARQL 的规范还不够了解，无法确定这在错误解决方法之外是否有意义，但您始终可以通过将查询包装为 SPARQL 1.1 子查询来"屏蔽"结果：

SELECT ?var1 ?var2 ... ?varn
{
...
}

"掩蔽"？varx变为

SELECT ?var1 ?var2 ... ?var(x-1) ?var(x+1) ... ?varn
{
SELECT ?var1 ?var2 ... ... ?varn
{
...
}
}