How many {medical examinations} are to/by {medical ultrasonography} ?
For medical ultrasonography, how many medical examinations are required?
How many medical examinations are required for medical ultrasonography} ?
SELECT ( COUNT ( ?e ) AS ?f ) { ?e property:medical_examinations resource:medical_ultrasonography }
SELECT (COUNT(?sub) AS ?subs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P923> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q234904 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P923 wd:Q234904 }
15