Обсуждение: Can I simplify this somehow?

I tried(!) to write this as a with (CTE), but failed.

Can one of the CTE experts (or better SQL writer) help me here?

-- generate a table of timestamps to match against
select
generate_series(date_trunc('day',now()-'45 days'::interval),now()+'1
hour'::inte
rval,'1 hour')
    AS thetime  into temp table timestamps;

-- get a count of logged in users for a particular time
SELECT thetime,case extract(dow  from thetime)
                when 0 then 'Sunday'
                when 1 then 'Monday'
                when 2 then 'Tuesday'
                when 3 then 'Wednesday'
                when 4 then 'Thursday'
                when 5 then 'Friday'
                when 6 then 'Saturday' end AS "Day", count(*) AS
"#LoggedIn"
FROM  timestamps,user_session
WHERE thetime BETWEEN login_time AND COALESCE(logout_time, now())
GROUP BY thetime
ORDER BY thetime;

Thanks for any help at all.


--
Larry Rosenman                     http://www.lerctr.org/~ler
Phone: +1 214-642-9640 (c)     E-Mail: ler@lerctr.org
US Mail: 108 Turvey Cove, Hutto, TX 78634-5688

On 2013-09-27 14:24, Adam Jelinek wrote:
> Are you looking for something like this for the result for the last 45
> days or something else?
>
> TIME  MON   TUE  WED ...
> 09:00     1        3       4
> 10:00     5        0       8
>
That would be cool, but just a list is good too.....



--
Larry Rosenman                     http://www.lerctr.org/~ler
Phone: +1 214-642-9640 (c)     E-Mail: ler@lerctr.org
US Mail: 108 Turvey Cove, Hutto, TX 78634-5688

On Fri, Sep 27, 2013 at 12:32 PM, Larry Rosenman <ler@lerctr.org> wrote:
> On 2013-09-27 14:24, Adam Jelinek wrote:
>> TIME  MON   TUE  WED ...
>> 09:00     1        3       4
>> 10:00     5        0       8
>>
> That would be cool, but just a list is good too.....

You need to take a look at this module:

http://www.postgresql.org/docs/9.3/static/tablefunc.html

Particularly look at the crostab(text, text) function.

-- 
Kind regards,
Sergey Konoplev
PostgreSQL Consultant and DBA

http://www.linkedin.com/in/grayhemp
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