RE: [GENERAL] Subselect question

> Hi,
> 
> I have some trouble with subselects. (Version 6.3).
> 
> If I try 
> 
> Select name, address from costumers where cod_costumer  in (
> Select cod_costumer from logins where total_usage > 0);
> 
> It take lots of time (really I din't wait till the end). 
> 
> But if I manualy split in 
> Select cod_costumer from logins where total_usage > 0;
> getting  
> ( 1,  9, 15, 18 , 40) 
> and then use
> Select name, address from costumers where cod_costumer  in ( 1,  9, 
> 15, 18 , 40);
> 
> All is OK. 
> 
> Is this type of subselect suported ? 
> 
> Thanks
>  Giovanni Floridia
> 

Yes it's supported, but the subselect will be executed for each row of
the main select.
This should be a faster select (but not as fast as your second one).
Select name, address from costumers where EXISTS(Select 1 from logins
where total_usage > 0 AND logins.cod_customer = customers.cod_customer);
	-DEJ