My revised code :)
$table->select_options("GROUP BY ID"); # Needed for query to work.
my $total = $table->select('COUNT(DISTINCT ID)')->fetchrow;
Code:
my $table = $DB->table('Links','Reviews'); $table->select_options("GROUP BY ID"); # Needed for query to work.
my $total = $table->select('COUNT(DISTINCT ID)')->fetchrow;