How about:

sub db_execute {
    my(@return, @a, $cursor);
    unless ($VARS{connected}) {db_connect(); $VARS{connected}++;}
    $cursor = $dbh->prepare($_[0]) || db_error();
    $cursor->execute || db_error();
    unless ($_[1]) {
        return @{ $cursor->fetchall_arrayref };
    }
}

my $SQL = "select a, b, c from my_table";
my @rows = db_execute($SQL);
for (@rows) {
  my @row = @$_;
  ...
}
[download]

(I'm not sure what the unless($_[1]) is for...)

Update: Use fetchall_arrayref() instead of looping over fetchrow().