Re: how to get row number in select query

From: Emi Lu <emilu(at)encs(dot)concordia(dot)ca>
To: Thomas Kellerer <spam_eater(at)gmx(dot)net>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: how to get row number in select query
Date: 2011-01-31 16:39:32
Message-ID: 4D46E5C4.8070208@encs.concordia.ca
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Ok, before 8.4, there I can use row_number().

For 8.3 + display tag + order by integer + paging based on pageBean

ArrayList<Bean> alist;

In Bean.java, added:

private int rec_num;

in main .action java:

for(int i=0 ; i<alist.size; i++)
{
Bean(i).setRec_num = (i+1);
...
}

This will let displaytag show rec num successfully.

--
Lu Ying

On 01/27/2011 10:30 AM, Thomas Kellerer wrote:
> Piotr Czekalski, 27.01.2011 16:21:
>> Gentelmen,
>>
>> I follow this thread and I don't exactly get an idea of yours, but
>> isn't is as simple as (example: table "web.files" contains one column
>> named "fileurl" ):
>>
>> select row_number() over(), X.fileurl from (select fileurl from
>> web.files order by fileurl) X
>>
>> The only disadvantage is that if you do want to order resultset you
>> have to use "select from select" as numbers are added before order
>> which may cause some performance troubles.
>>
>
> You can get the row_number() without using the sub-select and without
> ordering the whole result as you can specify the order in the over()
> clause:
>
> select fileurl
> row_number() over (order by fileurl)
> from web.files
>
> Regards
> Thomas
>
>

--
Emi Lu, ENCS, Concordia University, Montreal H3G 1M8
emilu(at)encs(dot)concordia(dot)ca +1 514 848-2424 x5884

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