尽管过滤器,DBpedia查询不止一次返回一些音乐剧

Question

我正在尝试对DBpedia使用SPARQL查询来检索音乐剧列表和一些相关属性.然而,尽管使用了适当的滤镜(据我所知),结果包括许多音乐剧不止一次.这是我的查询:

    PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
    PREFIX dbo: <http://dbpedia.org/ontology/>
    PREFIX dbpprop: <http://dbpedia.org/property/>
    SELECT ?label ?abstract ?book ?music ?lyrics
    WHERE { 
        ?play <http://purl.org/dc/terms/subject> <http://dbpedia.org/resource/Category:Broadway_musicals> ;
            rdfs:label ?label ;
            dbo:abstract ?abstract ;
            dbpprop:book ?book ;
            dbpprop:lyrics ?lyrics ;
            dbpprop:music ?music .
        FILTER (LANG(?label) = 'en')    
        FILTER (LANG(?abstract) = 'en')
        FILTER (LANG(?book) = 'en')
        FILTER (LANG(?lyrics) = 'en')
        FILTER (LANG(?music) = 'en')
    }

结果列表包含许多重复条目.在这里粘贴查询: DBpedia SPARQL Explorer,你会看到从'妈妈咪呀开始!' 列表中有很多重复项.

知道我缺少什么来获得独特的结果,没有重复？谢谢!

[由格伦麦克唐纳编辑,澄清它的音乐剧在这里"重复",而不是三重奏.]

Answer 1

SPARQL返回变量绑定.您的"重复"是投影属性中倍数的笛卡尔积.Mamma Mia有多位音乐作家和多位词作者,因此您可以获得可能在您的桌子中产生一排的所有可能的组合.

多么痛苦啊？"解决方案"是使用CONSTRUCT而不是SELECT,并处理返回图形而不是表格.也许是这样的:

http://dbpedia.org/snorql/?query=PREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0A++++ PREFIX + DBO%3A +%3Chttp%3A%2F%2Fdbpedia.org%2Fontology%2F%3E%0D 0A%++++ PREFIX + dbpprop%3A +%3Chttp%3A%2F%2Fdbpedia.org%2Fproperty%2F%3E %0D 0A%++++ CONSTRUCT +%7B%0D 0A%%++++++++ + 3Fplay RDFS%3Alabel +%3Flabel +%3B%0D 0A%DBO ++++++++++++%3Aabstract +%3Fabstract +%3B%0D %0A ++++++++++++ dbpprop%3Abook +%3Fbook +%3B%0D 0A%++++++++++++ dbpprop%3Alyrics +%3Flyrics +%3B%0D 0A%++ ++++++++++ dbpprop%3Amusic +%3Fmusic +.%0D 0A%++++%7D%0D 0A%++++ WHERE +%7B +%0D 0A%%++++++++ + 3Fplay%3Chttp%3A%2F%2Fpurl.org% 2Fdc%2Fterms%2Fsubject%3E +%3Chttp%3A%2F%2Fdbpedia.org%2Fresource%2FCategory%3ABroadway_musicals%3E +%3B%0D 0A%RDFS ++++++++++++%3Alabel +%3Flabel +%3B %0D 0A%DBO ++++++++++++%3Aabstract +%3Fabstract +%3B%0D 0A%++++++++++++ dbpprop%3Abook +%3Fbook +%3B%0D 0A% ++++++++++++ dbpprop%3Alyrics +%3Flyrics +%3B%0D 0A%++++++++++++ dbpprop%3Amusic +%3Fmusic +.%0D 0A%+++++ +++ FILTER +%28LANG%28%3Flabel%29 +%3D +%27en%27%29%++++ 0D 0A%FILTER ++++++++ +%28LANG%2 8%3Fabstract%29 +%3D +%27en%27%29%0D 0A%FILTER ++++++++ +%28LANG%28%3Fbook%29 +%3D +%27en%27%29%0D 0A%++ ++++++ FILTER +%28LANG%28%3Flyrics%29 +%3D +%27en%27%29%0D 0A%FILTER ++++++++ +%28LANG%28%3Fmusic%29 +%3D +%27en %27%29%0D 0A%++++%7D