- Go to https://query.wikidata.org/ and send the following SPARQL Query
## Frage nach Physiker, die eine Seite auf de.wiki und en.wiki haben, und ordne # das Datum nach dem Geburtstag im Jahr # #SELECT ( COUNT(?item) as ?numberOfPhysicists ) # result 4981 (in 28s) at 2019-09-08 # SELECT DISTINCT ?item ?itemLabel ?sitelink (YEAR(?date) as ?year) ?date WHERE { ?item wdt:P106/wdt:P279* wd:Q169470. # Tätigkeit '?classPhys', mit "property path" S 62-65 ?sitelink schema:isPartOf <https://de.wikipedia.org/>; schema:about ?item. ?site2link schema:isPartOf <https://en.wikipedia.org/>; schema:about ?item. ?item wdt:P569 ?date . BIND( 100*MONTH(?date) + DAY(?date) AS ?monthday ) BIND( YEAR( ?date ) AS ?xyear ) FILTER( ?xyear < 1580 ) SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". } } ORDER BY ?monthday LIMIT 6000
- send search in the result list "wd:Q619", that is Nikolaus Kopernikus,
- The birthday of Nikolaus Kopernikus is shown to be the 28. Februar 1473
- Now select the page "https://www.wikidata.org/wiki/Q619" the property "P569" (date of birth) shows 19 February 1473 which differs from the number in the result list by 9 days.
- This error happens also with other persons and with the date of death
- To me it seems that this error ist related to a wrong handling of Julian and Gregorian calender, may be in the MONTH- and DAY-Function of the SPARQL- implementation and in the formating of dates in the SPARQL-result- list.
I hope a correction will soon result to the same and correct date values for dates earlier than 1580
See also the discussion in the German Wikipedia