Baron Schwartz schrieb:
> Hi,
>
> On Wed, Apr 23, 2008 at 8:42 AM, Morten Primdahl <primdahl@stripped> wrote:
>> Hi,
>>
>> A user enters a date range (ie. 2 dates, '2008-04-01' and
>> '2008-04-03'), the problem is to determine how many open events exist
>> on each day in this interval.
>>
>> Assume that the "events" table has a "start_date" and an "end_date".
>> One way to solve this problem, is to create an inline view in the
>> query, eg.:
>>
>> SELECT virtual_date_range.index_date AS index_date, COUNT(*) AS
>> matches
>> FROM events, (
>> SELECT DATE('2008-04-01') AS index_date FROM DUAL UNION ALL
>> SELECT DATE('2008-04-02') FROM DUAL UNION ALL
>> SELECT DATE('2008-04-03') FROM DUAL UNION ALL
>> ) AS virtual_date_range
>> WHERE virtual_date_range.index_date >= events.start_date
>> AND virtual_date_range.index_date <= events.end_date
>> GROUP BY index_date;
>>
>> This works. But I'm wondering if there's a more elegant way of
>> expressing the same using pure DML, such that I don't need to build a
>> huge inline view in case the range is multiple years. Anyone?
>>
>> A solution that doesn't return any rows for the dates that do not have
>> an event would work.
>>
>> Example of the events table and the above query in action:
>> http://www.pastie.org/185419
>
> You can generate the values with the integers table.
> http://www.xaprb.com/blog/2005/12/07/the-integers-table/
i knew that you would answer this ... ;-)
--
Sebastian Mendel
