Re: returning only part of a rule set

On 25/11/14 22:24, David G Johnston wrote:

Thanks List,  I think this is the right way to go.

> Adrian Klaver-4 wrote
>>> If I am only interested in get 2 entries per result set,  I would expect
>>> to see
>> Actually <=2.
>> How do you determine which rows to keep, by id or something else?
>>
>>> 1 xx,yy
>>> 2 xx,yy
>>>
>>>
>>> 1,dd,zz
>>> 2,dd,zz
>>>
>>> 1, ee,ff
>>>
>>> Using LIMIT only gives
>>> 1 xx,yy
>>> 2 xx,yy
>>>
>>> Sorry for not explaining it very,  I want to limit the size of an
>>> inviduail set of records which is part of set of records.
>> It would help if we could see the actual query you are using to get the
>> result sets, suitably anonymized if needed.
> The general answer is that you use a window clause and a row_number()
> function over an appropriate partiton.  Put that in a subquery then in the
> outer query add a where clause for row_number <= 2.
>
> David J.
>
>
>
>
>
>
> --
> View this message in context: http://postgresql.nabble.com/returning-only-part-of-a-rule-set-tp5828217p5828226.html
> Sent from the PostgreSQL - general mailing list archive at Nabble.com.
>
>