Thread: grouping excluding some text results

grouping excluding some text results

From
"Fip"
Date:
Hi,

ho can I select some one restult for type, excluding the rest?
I have something like, as result of a join:

|   ID   |   score    |          description           |
-----------------------------------------------------------------
MG01      56           "textual description1..."
MG02      47           "another text ..."
MG02      55           "textual description, text...."        <----
note this
MG02      55           "textual description, text...."        <----
note this
MG01      35           "this is a different text...."
MG02      61           "random chars..."
(...)


I know that is possible selecting by grouping if I use an aggregate
function:
> select ID,max(score) by table group by ID
but I want the description too, only one description, and I have a very
large dataset, I cannot cycle with more subselections, this require too
much time; also I want to exclude duplicates: only one ID.

What can I do?


Re: grouping excluding some text results

From
John Sidney-Woollett
Date:
Off the top of my head (and not sure how optimized)...

select t1.id, t1.score, t1.description
from scoretable t1, (
   select id, max(score) as score
   from scoretable
   group by id
) as t2
where t1.id = t2.id
and t1.score = t2.score
order by t1.id

If you get duplicated rows back, then try using

select distinct t1.id, t1.score, t1.description ...

instead.

Hope that helps.

John

Fip wrote:
> Hi,
>
> ho can I select some one restult for type, excluding the rest?
> I have something like, as result of a join:
>
> |   ID   |   score    |          description           |
> -----------------------------------------------------------------
> MG01      56           "textual description1..."
> MG02      47           "another text ..."
> MG02      55           "textual description, text...."        <----
> note this
> MG02      55           "textual description, text...."        <----
> note this
> MG01      35           "this is a different text...."
> MG02      61           "random chars..."
> (...)
>
>
> I know that is possible selecting by grouping if I use an aggregate
> function:
>> select ID,max(score) by table group by ID
> but I want the description too, only one description, and I have a very
> large dataset, I cannot cycle with more subselections, this require too
> much time; also I want to exclude duplicates: only one ID.
>
> What can I do?
>
>
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