Re: can i make this sql query more efficiant?

<cut>
> select 
>     event, 
>     (select count(*) from baz a 
>         where level = 1 and a.event=baz.event) as ones, 
>     (select count(*) from baz a 
>         where level = 2 and a.event=baz.event) as twos, 
>     (select count(*) from baz a 
>         where level = 3 and a.event=baz.event) as threes
> from
>      baz
> group by 
>     event;
> 
> which gives me:
> 
>  event | ones | twos | threes 
> -------+------+------+--------
>  x     |    1 |    1 |      1
>  y     |    0 |    1 |      2
> (2 rows)
<cut>
What about this:
select event, sum(case when level=1 then 1 else 0 end) as ones, sum(case when level=2 then 1 else 0 end) as twos,
sum(casewhen level=3 then 1 else 0 end) as threes
 
from baz
group by event;

Regards,
Tomasz Myrta