field alias in where condition

[Havasvölgyi Ottó <h.otto@xxxxxxxxxxx>]

Hi all,

I issued the following queries:


select substring(proname from 1 to 1) as nevresz, count(*) 
from pg_proc 
where nevresz = 'a' 
order by nevresz 
group by nevresz;

select substring(proname from 1 to 1) as nevresz, count(*) 
from pg_proc 
order by nevresz 
group by nevresz;

The first query fails, and says that column 'nevresz' does not exist.
The second is OK.

What is the problem? I cannot use column alias in where condition?

Thanks,
Otto



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