How many {studies} are for {geology} ?
How many students are studying in {geology} ?
SELECT (COUNT(?obj) AS ?value ) { wd:Q1069 wdt:P2578 ?obj }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q1069> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P2578> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

What number of people are geology students?