Re: Generate a list of (days/hours) between two dates

Hopefully I'm understanding your question correctly. If so, maybe
this will do what you are wanting.

First, a couple of questions. Do you have this data in a table
already, and are looking to extract information based on the dates?
Or, are you basically wanting something like a for loop so you can
generate the dates between start and stop values?

If the former, and I understand what you are looking to accomplish,
here's one way to do it:

select timestampfield::date::timestamp as "date", count(*) from table
where timestampfield between start and stop group by "date" order by
"date";

should yield:
YYYY-MM-DD 00:00:00 #

for hours, use :

select (substr(timestampfield, 1, 13) || ':00:00')::timestamp as
"hourly", count(*) from table where timestampfield between start and
stop group by "hourly" order by "hourly";

should yield:
YYYY-MM-DD HH:00:00 #

Of course, this assumes your database already has this information.

i hope this helps.
Greg

On Jun 27, 2005, at 10:30 AM, ben(dot)hallert(at)gmail(dot)com wrote:

> Hi guys,
>
> I've scoured the date/time functions in the docs as well as
> google-grouped as many different combinations as I could think of to
> figure this out without asking, but I'm having no luck.
>
> I'd like to make a query that would return a list of every trunc'd
> TIMESTAMPs between two dates. For example, I'd want to get a list of
> every date_trunc('hour',whatever) between 6-1-2005 and 6-10-2005 and
> get a list that looks like:
>
> 6-1-2005 00:00:00
> 6-1-2005 01:00:00
> 6-1-2005 02:00:00
> etc
>
> Conversely, I want to generate a list of every day between two dates,
> like:
>
> 6-1-2005 00:00:00
> 6-2-2005 00:00:00
> 6-3-2005 00:00:00
>
> I know there's gotta be some way to do this in a SELECT function, but
> I'm running into a brickwall. I'm trying to take some of my date
> handling logic out of code and use the db engine so I can spend less
> time developing/maintaining code when mature date handling already
> exists in a resource I've already got loaded.
>
> Any thoughts?
>
>
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