agipamp's questions

Se eu tiver uma tabela simples chamada: conn_log no meu Redshift/Postgresql

No desempenho da view, qual a diferença entre esses dois comandos?

select t1.wifi_name, (t2.sconn*100)::numeric/t1.ttconn
from (select wifi_name, count(*) as ttconn 
      from conn_log 
      group by wifi_name) t1, 
     (select wifi_name, count(*) as sconn 
      from conn_log 
      where success = 1 
      group by wifi_name) t2
where t1.wifi_name = t2.wifi_name;

segunda consulta:

select t1.wifi_name, (t2.sconn*100)::numeric/t1.ttconn
from (select wifi_name, count(*) as ttconn 
      from conn_log 
      group by wifi_name) t1
join
     (select wifi_name, count(*) as sconn 
      from conn_log 
      where success = 1 
      group by wifi_name) t2
on t1.wifi_name = t2.wifi_name