That would be something along the lines of: 
my $prev;
my $data;

while ( $data = $sth->fetchrow_arrayref )  
{
    conditional_print ($data, $prev);
    $prev = $data;
}

#repeat for last record
conditional_print ($data, $prev);

$sth->finish;
$dbh->disconnect;

sub conditional_print
{
    my $data = shift;
    my $prev = shift;
    
    if 
    ( 
        $data->[0] eq $prev->[0] && 
        $data->[1] eq $prev->[1] && 
        $data->[2] eq $prev->[2] 
    )
    {
        print $data->[4], "\n";
    }
    else
    {
        print join ("\t", @{$data}), "\n";
    }
}

[download]
Basically you just have to remember the previous record somewhere.


holli, /regexed monk/

In reply to Re: compare current row with previous row by holli
in thread compare current row with previous row by Anonymous Monk

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.