[英]select combination of two columns sql, h2
如果此查詢返回任何行,那么您將確切地得到carrier
+ flight
的哪個組合有多個來源
select carrier, flight, count(distinct origin) as number_of_origins
from flights
group by carrier, flight
having count(distinct origin) >= 2;
此查詢告訴您是否有與多個origin
相關的任何carrier
+ flight
組合:
select carrier, flight
from flights
group by carrier, flight
having count(distinct origin) > 1
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