$sth = $dbh->prepare(<<SQL);
    
    SELECT * FROM mytable
    WHERE mydate between ? and ?
    ORDER BY mydate ASC
SQL

$sth->execute($start_date, $end_date);
my $res = $sth->fetchall_arrayref;

##</code><code>##

$sth = $dbh->prepare(<<SQL);
    
    SELECT * FROM mytable
    WHERE ? - mydate <= 15 -- this should really use the date/time functions instead
    ORDER BY mydate ASC
SQL

$sth->execute($end_date);
my $res = $sth->fetchall_arrayref;