{"id":"https://openalex.org/W1999049787","doi":"https://doi.org/10.1016/0306-4379(89)90050-1","title":"Nurql: A nested universal relation query language","display_name":"Nurql: A nested universal relation query language","publication_year":1989,"publication_date":"1989-01-01","ids":{"openalex":"https://openalex.org/W1999049787","doi":"https://doi.org/10.1016/0306-4379(89)90050-1","mag":"1999049787"},"language":"en","primary_location":{"id":"doi:10.1016/0306-4379(89)90050-1","is_oa":false,"landing_page_url":"https://doi.org/10.1016/0306-4379(89)90050-1","pdf_url":null,"source":{"id":"https://openalex.org/S193006928","display_name":"Information Systems","issn_l":"0306-4379","issn":["0306-4379","1873-6076"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310320990","host_organization_name":"Elsevier BV","host_organization_lineage":["https://openalex.org/P4310320990"],"host_organization_lineage_names":["Elsevier BV"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Information Systems","raw_type":"journal-article"},"type":"article","indexed_in":["crossref"],"open_access":{"is_oa":false,"oa_status":"closed","oa_url":null,"any_repository_has_fulltext":false},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5015725705","display_name":"Mark Levene","orcid":"https://orcid.org/0000-0001-8632-4732"},"institutions":[{"id":"https://openalex.org/I98259816","display_name":"Birkbeck, University of London","ror":"https://ror.org/02mb95055","country_code":"GB","type":"education","lineage":["https://openalex.org/I124357947","https://openalex.org/I98259816"]}],"countries":["GB"],"is_corresponding":false,"raw_author_name":"M. Levene","raw_affiliation_strings":["Department of Computer Science, Birkbeck College, University of London, Malet Street, London WC1E 7HX, U.K"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Department of Computer Science, Birkbeck College, University of London, Malet Street, London WC1E 7HX, U.K","institution_ids":["https://openalex.org/I98259816"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5024905226","display_name":"George Loizou","orcid":"https://orcid.org/0000-0002-9376-9243"},"institutions":[{"id":"https://openalex.org/I98259816","display_name":"Birkbeck, University of London","ror":"https://ror.org/02mb95055","country_code":"GB","type":"education","lineage":["https://openalex.org/I124357947","https://openalex.org/I98259816"]}],"countries":["GB"],"is_corresponding":false,"raw_author_name":"G. Loizou","raw_affiliation_strings":["Department of Computer Science, Birkbeck College, University of London, Malet Street, London WC1E 7HX, U.K"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Department of Computer Science, Birkbeck College, University of London, Malet Street, London WC1E 7HX, U.K","institution_ids":["https://openalex.org/I98259816"]}]}],"institutions":[],"countries_distinct_count":1,"institutions_distinct_count":2,"corresponding_author_ids":[],"corresponding_institution_ids":[],"apc_list":{"value":2970,"currency":"USD","value_usd":2970},"apc_paid":null,"fwci":1.02,"has_fulltext":false,"cited_by_count":4,"citation_normalized_percentile":{"value":0.77765349,"is_in_top_1_percent":false,"is_in_top_10_percent":false},"cited_by_percentile_year":{"min":89,"max":94},"biblio":{"volume":"14","issue":"4","first_page":"307","last_page":"316"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T10317","display_name":"Advanced Database Systems and Queries","score":0.9998000264167786,"subfield":{"id":"https://openalex.org/subfields/1705","display_name":"Computer Networks and Communications"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T10317","display_name":"Advanced Database Systems and Queries","score":0.9998000264167786,"subfield":{"id":"https://openalex.org/subfields/1705","display_name":"Computer Networks and Communications"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T11106","display_name":"Data Management and Algorithms","score":0.9995999932289124,"subfield":{"id":"https://openalex.org/subfields/1711","display_name":"Signal Processing"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10215","display_name":"Semantic Web and Ontologies","score":0.9994999766349792,"subfield":{"id":"https://openalex.org/subfields/1702","display_name":"Artificial Intelligence"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/computer-science","display_name":"Computer science","score":0.8374874591827393},{"id":"https://openalex.org/keywords/query-language","display_name":"Query language","score":0.7238145470619202},{"id":"https://openalex.org/keywords/relational-database","display_name":"Relational database","score":0.6759085655212402},{"id":"https://openalex.org/keywords/nested-set-model","display_name":"Nested set model","score":0.5496101379394531},{"id":"https://openalex.org/keywords/sargable","display_name":"Sargable","score":0.5492104291915894},{"id":"https://openalex.org/keywords/query-optimization","display_name":"Query optimization","score":0.5361535549163818},{"id":"https://openalex.org/keywords/view","display_name":"View","score":0.5248163938522339},{"id":"https://openalex.org/keywords/rdf-query-language","display_name":"RDF query language","score":0.5167728662490845},{"id":"https://openalex.org/keywords/query-by-example","display_name":"Query by Example","score":0.4656117260456085},{"id":"https://openalex.org/keywords/relational-model","display_name":"Relational model","score":0.4643210768699646},{"id":"https://openalex.org/keywords/data-control-language","display_name":"Data control language","score":0.45501577854156494},{"id":"https://openalex.org/keywords/relational-calculus","display_name":"Relational calculus","score":0.4260011613368988},{"id":"https://openalex.org/keywords/programming-language","display_name":"Programming language","score":0.40920743346214294},{"id":"https://openalex.org/keywords/database-design","display_name":"Database design","score":0.3980419337749481},{"id":"https://openalex.org/keywords/information-retrieval","display_name":"Information retrieval","score":0.34512683749198914},{"id":"https://openalex.org/keywords/theoretical-computer-science","display_name":"Theoretical computer science","score":0.32878297567367554},{"id":"https://openalex.org/keywords/web-query-classification","display_name":"Web query classification","score":0.30697035789489746},{"id":"https://openalex.org/keywords/web-search-query","display_name":"Web search query","score":0.28146523237228394},{"id":"https://openalex.org/keywords/search-engine","display_name":"Search engine","score":0.09706124663352966}],"concepts":[{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.8374874591827393},{"id":"https://openalex.org/C192028432","wikidata":"https://www.wikidata.org/wiki/Q845739","display_name":"Query language","level":2,"score":0.7238145470619202},{"id":"https://openalex.org/C5655090","wikidata":"https://www.wikidata.org/wiki/Q192588","display_name":"Relational database","level":2,"score":0.6759085655212402},{"id":"https://openalex.org/C103000020","wikidata":"https://www.wikidata.org/wiki/Q1978426","display_name":"Nested set model","level":3,"score":0.5496101379394531},{"id":"https://openalex.org/C192939062","wikidata":"https://www.wikidata.org/wiki/Q104840822","display_name":"Sargable","level":4,"score":0.5492104291915894},{"id":"https://openalex.org/C157692150","wikidata":"https://www.wikidata.org/wiki/Q2919848","display_name":"Query optimization","level":2,"score":0.5361535549163818},{"id":"https://openalex.org/C54239708","wikidata":"https://www.wikidata.org/wiki/Q1329910","display_name":"View","level":3,"score":0.5248163938522339},{"id":"https://openalex.org/C96956885","wikidata":"https://www.wikidata.org/wiki/Q6138701","display_name":"RDF query language","level":5,"score":0.5167728662490845},{"id":"https://openalex.org/C194222762","wikidata":"https://www.wikidata.org/wiki/Q114486","display_name":"Query by Example","level":4,"score":0.4656117260456085},{"id":"https://openalex.org/C40207289","wikidata":"https://www.wikidata.org/wiki/Q755662","display_name":"Relational model","level":3,"score":0.4643210768699646},{"id":"https://openalex.org/C32977378","wikidata":"https://www.wikidata.org/wiki/Q604737","display_name":"Data control language","level":5,"score":0.45501577854156494},{"id":"https://openalex.org/C99436015","wikidata":"https://www.wikidata.org/wiki/Q1722436","display_name":"Relational calculus","level":4,"score":0.4260011613368988},{"id":"https://openalex.org/C199360897","wikidata":"https://www.wikidata.org/wiki/Q9143","display_name":"Programming language","level":1,"score":0.40920743346214294},{"id":"https://openalex.org/C148840519","wikidata":"https://www.wikidata.org/wiki/Q1049878","display_name":"Database design","level":2,"score":0.3980419337749481},{"id":"https://openalex.org/C23123220","wikidata":"https://www.wikidata.org/wiki/Q816826","display_name":"Information retrieval","level":1,"score":0.34512683749198914},{"id":"https://openalex.org/C80444323","wikidata":"https://www.wikidata.org/wiki/Q2878974","display_name":"Theoretical computer science","level":1,"score":0.32878297567367554},{"id":"https://openalex.org/C118689300","wikidata":"https://www.wikidata.org/wiki/Q7978614","display_name":"Web query classification","level":4,"score":0.30697035789489746},{"id":"https://openalex.org/C164120249","wikidata":"https://www.wikidata.org/wiki/Q995982","display_name":"Web search query","level":3,"score":0.28146523237228394},{"id":"https://openalex.org/C97854310","wikidata":"https://www.wikidata.org/wiki/Q19541","display_name":"Search engine","level":2,"score":0.09706124663352966}],"mesh":[],"locations_count":1,"locations":[{"id":"doi:10.1016/0306-4379(89)90050-1","is_oa":false,"landing_page_url":"https://doi.org/10.1016/0306-4379(89)90050-1","pdf_url":null,"source":{"id":"https://openalex.org/S193006928","display_name":"Information Systems","issn_l":"0306-4379","issn":["0306-4379","1873-6076"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310320990","host_organization_name":"Elsevier BV","host_organization_lineage":["https://openalex.org/P4310320990"],"host_organization_lineage_names":["Elsevier BV"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Information Systems","raw_type":"journal-article"}],"best_oa_location":null,"sustainable_development_goals":[],"awards":[],"funders":[],"has_content":{"grobid_xml":false,"pdf":false},"content_urls":null,"referenced_works_count":49,"referenced_works":["https://openalex.org/W23033777","https://openalex.org/W115732867","https://openalex.org/W135323631","https://openalex.org/W180578187","https://openalex.org/W1502402741","https://openalex.org/W1540464923","https://openalex.org/W1561760692","https://openalex.org/W1573833643","https://openalex.org/W1721126460","https://openalex.org/W1974100509","https://openalex.org/W1983428002","https://openalex.org/W2001665375","https://openalex.org/W2005471433","https://openalex.org/W2008296878","https://openalex.org/W2025583905","https://openalex.org/W2027218717","https://openalex.org/W2038271811","https://openalex.org/W2049652711","https://openalex.org/W2057852703","https://openalex.org/W2065419751","https://openalex.org/W2066837227","https://openalex.org/W2081053428","https://openalex.org/W2089677381","https://openalex.org/W2089781037","https://openalex.org/W2093882190","https://openalex.org/W2095263945","https://openalex.org/W2104498537","https://openalex.org/W2115822498","https://openalex.org/W2121214732","https://openalex.org/W2140136514","https://openalex.org/W2150111014","https://openalex.org/W2489748212","https://openalex.org/W2788164529","https://openalex.org/W6600961000","https://openalex.org/W6604826896","https://openalex.org/W6605531863","https://openalex.org/W6630000821","https://openalex.org/W6631393269","https://openalex.org/W6632360649","https://openalex.org/W6633876246","https://openalex.org/W6634386353","https://openalex.org/W6637754542","https://openalex.org/W6650750969","https://openalex.org/W6651504578","https://openalex.org/W6652430804","https://openalex.org/W6662764068","https://openalex.org/W6673976005","https://openalex.org/W6678348209","https://openalex.org/W6682089088"],"related_works":["https://openalex.org/W2400419823","https://openalex.org/W1548279772","https://openalex.org/W4240833292","https://openalex.org/W3036348878","https://openalex.org/W4250894256","https://openalex.org/W1585732288","https://openalex.org/W2176771627","https://openalex.org/W1489445454","https://openalex.org/W3081572596","https://openalex.org/W2036832324"],"abstract_inverted_index":null,"counts_by_year":[{"year":2021,"cited_by_count":1}],"updated_date":"2026-06-11T09:08:48.828518","created_date":"2025-10-10T00:00:00"}