my $select = $dbh->prepare("select email,password from users where username=?");
  $select->execute( $username );
  my @row = $select->fetchrow_array;
  if ( @row != 2 or $email ne $row[0] or $password ne $dbpassword ) {
     push @error_mesgs, "bad login...";
  } else {
     #login was okay, so redirect...
  }