Doesn't seem that hard. The code below outputs the BUG_Comments_COMBINED.csv file, though it doesn't worry at all about the order in which it outputs lines. If that matters to you, it can be adjusted. 
#!/usr/bin/perl -l
use strict;
use warnings;

my %comment; #comment for each bug id
<DATA>; #skip header line
while(<DATA>){
    chomp;
    #the 4 in the split below ignores all comma in the comment text
    my (undef, $bugid, $date, $body) = split(/,/, $_, 4); 
    $comment{$bugid} .= "$date $body ";
}

while (my ($id, $comment) = each %comment){
    print "$id, $comment";
}

__DATA__
CommentId, BugId, Date, CommentBody
1023,9555,03/06/2008,This is the body
1024,9555,03/07/2008,This is the body
1025,9555,03/08/2008,This is the body

[download]

In reply to Re: One to Many is Too Many? by Eimi Metamorphoumai
in thread One to Many is Too Many? by Jamin

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.