Re: select function alias

On 30/11/2016 13:42, Timoteo Blanco wrote:
> Howdy,
>
> I've a series of timestamp columns I'd like to alias in select
> statements. psql indicates my alias doesnt exist after
> I define it.
>
> Example -> select to_char(impressions_create_date,'yyyy-mm-dd') as ymd
> from impressionsdb where ymd like '2016-11%' ;
>
> psql always complains column ymd does not exist. I've inherited a
> series of tables with many timestamps and would like to
> shorten the select in queries without renaming any columns.
>
>
> postgresql 9.2 on Gentoo 4.4.26
>
> TIA, TRB
>

3 options:

1. Use the same to_char expression in the where clause
2. Use a sub-select to use the alias in the outer where clause
3. Use the original column in the where clause and use the timestamp
comparisson functions.

Howard.