It really does come down to "it depends on what you are doing." You really have to know your database and your perl very well. In general, I leave most things to the database if possible, and use the SQL to return the smallest, most refined result set back to the script as possible. One thing that I almost always do with perl however, is sorting... SQL cannot touch some of perl's beauty in sorting: 
my $unsorted = $dbh->selectall_arrayref($FOOSQL) or 
  die "Fooey, foo failed ($FOOSQL) $DBI::errstr\n";
for (
sort {
  $Q::SortBy == 1 ? 
    ($a->[1] cmp $b->[1] or $a->[4] cmp $b->[4] or $a->[2] cmp $b->[2]
+) :
  $Q::SortBy == 2 ? 
    ($a->[1] cmp $b->[1] or $a->[2] cmp $b->[2]) : 
    ($b->[3] <=> $a->[3] or $a->[2] cmp $b->[2])
}
map {[$_, lc $_->[5], substr($_->[4],3,3), int $_->[1], lc $_->[3]]} @
+$unsorted) {
  ## Do something with $_ here...
}

[download]

In reply to Re: Replacing SQL with perl by turnstep
in thread Replacing SQL with perl by marvell

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.