Re: Reverse String in sql or pgplsql

Hi,

Could someone please give a hint on how to query the following neatly ?

Get news from a news table that belong to a particular account, get segment
name from segments table for each news item and read count from read history
table that gets a news_id and timestamp insert every time the news is read.
Display everything by news count, most read news first ?

news_id 4, news_header, segment_name x, read 10 times
news_id 2, news_header, segment_name y, read 8 times
news_id 1, news_header, segment_name x, read 7 times
news_id 3, news_header, segment_name x, read 0 times

news_table:
news_id, account_id, segment_id, news_header, ...

segments_table:
segment_id, account_id, segment_name

read_history_table:
history_id, news_id, timestamp

TIA,

Aarni
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On Thu, 2005-02-24 at 17:17 +0200, Aarni Ruuhimäki wrote:
> Hi,
>
> Could someone please give a hint on how to query the following neatly ?
>
> Get news from a news table that belong to a particular account, get segment
> name from segments table for each news item and read count from read history
> table that gets a news_id and timestamp insert every time the news is read.
> Display everything by news count, most read news first ?
>
> news_id 4, news_header, segment_name x, read 10 times
> news_id 2, news_header, segment_name y, read 8 times
> news_id 1, news_header, segment_name x, read 7 times
> news_id 3, news_header, segment_name x, read 0 times
>
> news_table:
> news_id, account_id, segment_id, news_header, ...
>
> segments_table:
> segment_id, account_id, segment_name
>
> read_history_table:
> history_id, news_id, timestamp
>

how about:

select news_id,news_header,segment_name,count(*)
from news_table
natural join segments_table
natural join read_history_table
where account_id=?
group by news_id,news_header,segment_name;

?

gnari

Did some searching on forums archives to no avail, I found a PL/Perl example but would like to do this in plpgsql if possible. Does somebody have this sitting around, I just dont want to reinvent the wheel. But if need to I will.

Thanks in advance,

Oisin

On Saturday 26 February 2005 11:55 am, Oisin Glynn wrote:
> Did some searching on forums archives to no avail, I found a PL/Perl
> example but would like to do this in plpgsql if possible. Does somebody
> have this sitting around, I just dont want to reinvent the wheel. But if
> need to I will.
>
> Thanks in advance,
>
> Oisin
CREATE FUNCTION reverse(text) RETURNS text
AS $_$
DECLARE
original alias for $1;
reverse_str text;
i int4;
BEGIN
reverse_str := '';
FOR i IN REVERSE LENGTH(original)..1 LOOP
reverse_str := reverse_str || substr(original,i,1);
END LOOP;
RETURN reverse_str;
END;$_$
LANGUAGE plpgsql IMMUTABLE;

from a posting a while back.

create or replace function reverse_string(text) returns text as
'
DECLARE
reversed_string text;
incoming alias for $1;

BEGIN

reversed_string = '''';

for i in reverse char_length(incoming)..1 loop

reversed_string = reversed_string || substring(incoming from i for 1);

end loop;

return reversed_string;

END'
language plpgsql;

select * from reverse_string('Postgres');

reverse_string
sergtsoP

On Feb 26, 2005, at 11:55 AM, Oisin Glynn wrote:

> Did some searching on forums archives to no avail, I found a 
> PL/Perl example but would like to do this in plpgsql if possible. Does
> somebody have this sitting around, I just dont want to reinvent the
> wheel.  But if need to I will.
>  
> Thanks in advance,
>  
> Oisin
>
Bradley Miller
NUVIO CORPORATION
Phone: 816-444-4422 ext. 6757
Fax: 913-498-1810
http://www.nuvio.com
bmiller(at)nuvio(dot)com

Hi,

Thanks Ragnar. This, and an other GROUP BY + name query within output got me
there.

<cfquery name="get_news" datasource="#ds#">
SELECT DISTINCT news_id, news_header, segment, segment_id, count(*)
FROM news_table
NATURAL JOIN segments_table
NATURAL JOIN read_history
WHERE account_id = #Url.account_id#
GROUP BY news_id, news_header, segment, segment_id ORDER BY count DESC
</cfquery>
...
<cfoutput query="get_news" group="news_id">

<cfquery name="get_seg" datasource="#ds#">
SELECT segment_name
FROM segments_table
WHERE segment_id = #segment#

</cfquery>

#news_header# - #get_seg.segment_name# - #count#

</cfoutput>

On Saturday 26 February 2005 15:24, you wrote:
> On Thu, 2005-02-24 at 17:17 +0200, Aarni Ruuhimäki wrote:
> > Hi,
> >
> > Could someone please give a hint on how to query the following neatly ?
> >
> > Get news from a news table that belong to a particular account, get
> > segment name from segments table for each news item and read count from
> > read history table that gets a news_id and timestamp insert every time
> > the news is read. Display everything by news count, most read news first
> > ?
> >
> > news_id 4, news_header, segment_name x, read 10 times
> > news_id 2, news_header, segment_name y, read 8 times
> > news_id 1, news_header, segment_name x, read 7 times
> > news_id 3, news_header, segment_name x, read 0 times
> >
> > news_table:
> > news_id, account_id, segment, news_header, ...
> >
> > segments_table:
> > segment_id, account_id, segment_name
> >
> > read_history_table:
> > history_id, news_id, timestamp
>
> how about:
>
> select news_id,news_header,segment_name,count(*)
> from news_table
> natural join segments_table
> natural join read_history_table
> where account_id=?
> group by news_id,news_header,segment_name;
>
> ?
>
> gnari
>
>
>
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> TIP 7: don't forget to increase your free space map settings

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