my $sth_prepare = $dbh1->prepare("select count(id) from userlog group by substring(datestamp,1,10)");
$sth_prepare->execute() or die $DBI::errstr;

print "Content-Type: text/html\n\n";
my $list;
for ($sth_prepare->fetchrow_array()) {
   $list .= "$_<br>";
}
print $list;