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Sequel: Get latest record of multiple

Florian Aßmann

6/4/2007 5:15:00 AM

Hi there,

first of all I'd like to say that Sequel seems very promising, thank
you Sharon. I'm currently writing a threaded daemon and I can't
figure out how to build this SQL String.

I have an array of category ids which I use to select import records:
db[:imports].filter :category_id => categories.map(:id)

Since a category has multiple imports I only want the latest Import
before a Date X for each category. Is this even possible?

Sincerely
Florian
2 Answers

Alin Popa

6/4/2007 6:26:00 AM

0

Florian AÃ?mann wrote:
> Hi there,
>
> first of all I'd like to say that Sequel seems very promising, thank
> you Sharon. I'm currently writing a threaded daemon and I can't
> figure out how to build this SQL String.
>
> I have an array of category ids which I use to select import records:
> db[:imports].filter :category_id => categories.map(:id)
>
> Since a category has multiple imports I only want the latest Import
> before a Date X for each category. Is this even possible?
>
> Sincerely
> Florian

Hi Florian,

I think that you need a field in that table in which you have to put the
timestamp. Maybe this feature that you want is present in some advanced
RDBMS like Oracle/DB2 or maybe Postgresql.

Best regards,

Alin

--
Posted via http://www.ruby-....

Florian Aßmann

6/4/2007 10:06:00 PM

0

Hi Alin,

Am 04.06.2007 um 08:26 schrieb Alin Popa:

>> first of all I'd like to say that Sequel seems very promising, thank
>> you Sharon. I'm currently writing a threaded daemon and I can't
>> figure out how to build this SQL String.
>>
>> I have an array of category ids which I use to select import records:
>> db[:imports].filter :category_id => categories.map(:id)
>>
>> Since a category has multiple imports I only want the latest Import
>> before a Date X for each category. Is this even possible?
>
> Hi Florian,
>
> I think that you need a field in that table in which you have to
> put the
> timestamp. Maybe this feature that you want is present in some
> advanced
> RDBMS like Oracle/DB2 or maybe Postgresql.

I defined some methods in my Model that - hopefully - build me up the
query, still needs to be tested though. As the moment I'm having
sequence problems when I try to create Records... :(

Sincerely
Florian

P.S. I'm using PostgreSQL 8.1