You've probably noticed the topic is "Semi-OT". That's there because I am conflicted. My problem is not entirely centered about Perl (I used Perl as a Procedural language in PostgreSQL), but I have gotten to know that there is a breadth of knowledge here on other topics as well, due to the real-life experiences of my fellow monks. Now I am faced with a problem that may have been experienced by some of you out there, but I have no other effecient way of presenting you with it for advice.

So, I'll post here not seeking Perl Wisdom specifically, but seeking Wisdom of the Monks:

I have a sub in a Perl script that loops fetching the following statement (prepare once, execute once, a while loop for fetchrow_array)

SELECT url,name FROM links
And formats it like so:
<a href='$url'>$name</a><br>
A variable ($link_list) is in the loop, holding the concatenated last statement with the new one.

I would rather do this with FUNCTIONS (and/or AGGREGATES).

So, I CREATEd a FUNCTION:

CREATE FUNCTION format_link(text,text) RETURNS text AS ' return qq[<a href="http://www.domain.com/$_[0]" class="body_link">$_ +[1]</a>]; ' LANGUAGE 'plperl';
So in my Perl script, the SQL statement becomes:
SELECT format_link(url,name) FROM links
However, I still have to loop with Perl -- it would be nice to use an AGGREGATE to do some of this for me.

I can create an AGGREGATE but from what I can tell, the format of the sfunc can only have two parameters like so:

sfunc_name(type,type)
Where the first parameter is what was passed before, and the second parameter is the 'new' info to do stuff to. Is it not possible to do something similar to?:
sfunc_name(type,type,type)
So that I can pass the url and name to the AGGREGATE (so it can in turn pass it to the sfunc)? Where the sfunc could be something like so:
CREATE FUNCTION link_agg (text,text,text) RETURNS text AS ' return $_[0] . qq[<a href="http://www.domain.com/$_[0]" class="body_ +link">$_[1]</a><br>]; ' LANGUAGE 'plperl';
Because then I gain benefit of a stored procedure and cut the SQL in the script down to:
SELECT link_agg(url,name) FROM link;
Which will return the entire list at once, instead of needing the script to loop through multiple fetches.

...

Of course, I may be going about this in an entirely incorrect manner. Telling me so, with a bit of direction, would also be greatly appreciated.

--
notsoevil
--
Jeremiah 49:32 - And their camels shall be a booty. . .


In reply to Semi-OT: Functions and Aggregates in PostgreSQL by notsoevil

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