Re: SELECT and DATE Function question

On 9/10/06, Mike C <smith(dot)not(dot)western(at)gmail(dot)com> wrote:
>
> Hi,
>
> I'm trying to calculate an expiration date by adding the number of days
> onto the start date. i.e. select start_date + number_of_days from blah;
>
> create table blah (start_date timestamp, number_of_days integer);
> insert into blah values (current_timestamp, 25);
> select start_date + number_of_days from blah;
>
> The error I get is:
>
> ERROR: operator does not exist: timestamp without time zone + integer
> HINT: No operator matches the given name and argument type(s). You may
> need to add explicit type casts.
>
> But according to
> http://www.postgresql.org/docs/8.1/static/functions-datetime.html the +
> operator should support integers and treat them as days ( date
> '2001-09-28' + integer '7'). Obviously typing a constant into the query is a
> lot different from using the value of a column, but I would have thought it
> would work.
>
> What is the correct way to make this calculation?
>

Use:

select start_date + (cast(number_of_days as text) || ' days')::interval from
blah

See http://www.postgresql.org/docs/8.1/interactive/functions-datetime.htmlfor
more

==================================================================
Aaron Bono
Aranya Software Technologies, Inc.
http://www.aranya.com
http://codeelixir.com
==================================================================