How many {significant drug interaction} are to/by {erythromycin} ?
What is the number of symptoms caused by erythromycin?
How many symptoms are caused by erythromycin?
SELECT ( COUNT ( ?d ) AS ?g ) { ?d property:significant_drug_interaction resource:erythromycin }
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/P769> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q213511 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P769 wd:Q213511 }
42