Re: Top 10 airports referenced from a table of flights

[Rick James]

select apid, count(*) as ct
   from (
      select src_apid as apid
         from flights
   UNION
      select dst_apid as apid
         from flights
        ) x
   group by apid
   order by count(*) desc
   limit 10;

select x.apid, sum(x.ct) as ct
   from ( select src_apid as apid, count(*) as ct
             from flights
          UNION
          select src_apid as apid, count(*) as ct
             from flights ) x
   group by apid
   order by ct desc
   limit 10;