use DBI; 
use CGI ':standard'; 
print "Content-type: text/html\n\n";
my $dbh = DBI->connect('dbi:mysql:my_db','searcher','searcherpasswd')
or die "Connection Error: $DBI::errstr\n";
$sth = $dbh->prepare ("DELETE FROM my table where DATE <UNIX_TIMESTAMP(DATE_SUB(NOW()-INTERVAL 30 DAY)");
$sth->execute ();