Is it just a typo? "pckga" is not the same as "pckg2".

$pack = getfilenamefromdb(); # The path or .pm is not part of the pack
+age name.
require "pckg1/pckg2/$pack.pm";
no strict 'refs';
$result = ${"pckg1::pckg2::$pack\::"}{func}->();
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The code that you suggested did work perfectly but i did not understand the concept behind it. It would be good if you can tell me what exactly is happening there. Also why did the following did not work

require pckg1::pckg2::$filename;
$result= pckg1::pckg2::$filename::functionname(argument list)
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the above one is giving the error of BAD code after ::

See the documentation of require. It expects a version or expression as an argument. pckg1::pckg2::$filename is neither one. Namespace can't be built dynamically, you have to access the symbol table to do that. In my code, I use the form of require that isn't a bareword, so it's understood as a filename (that's why I add ".pm" to it). To be able to access the symbol table, you have to turn strict refs off. Then, you can reference the symbol table of a namespace as a hash of the same name plus ::. See Of Symbol Tables and Globs to learn more about symbol tables.
لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

And note that the name space the function appears in is the name space given in the package statement (if any) of the .pm file you just loaded, and is not necessarily derived from the file name at all.

It is true that the normal Perl module loading mechanism needs file Foo/Bar/Baz.pm to provide name space Foo::Bar::Baz, but when you are hand-loading modules like that, anything goes.

I'm not on a system were I can test this so It may need a slight adjustment, but it's the direction that I'd look into using.

#!/usr/bin/perl

use strict;
use warnings;
use Module::Load;
use lib './pckg1/pckg2';

my $filename = getfilenamefromdb();
autoload $filename;

my $result = func();
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