Grouping MySQL data

У меня есть эта таблица, назовем ее таблицей 1.

+----+---------+-----------------+
| id | link_id | url             |
+----+---------+-----------------+
|  1 |       1 | www.example.com |
|  2 |       1 | www.abc.com     |
|  3 |       1 | www.test.com    |
|  4 |       1 | www.t1.com      |
|  5 |       1 | www.newtest.com |
|  6 |       1 | www.testing.com |
|  7 |       1 | www.abc.com     |
|  8 |       1 | www.example.com |
|  9 |       1 | www.web1.com    |
| 10 |       1 | www.web2.com    |
| 11 |       2 | www.dear.com    |
| 12 |       2 | www.google.com  |
| 13 |       2 | www.flowers.com |
| 14 |       2 | www.yahoo.com   |
| 15 |       2 | www.abc.com     |
| 16 |       2 | www.dell.com    |
| 17 |       2 | www.web.com     |
| 18 |       2 | www.example.com |
| 19 |       2 | www.test.com    |
| 20 |       2 | www.abc.com     |
+----+---------+-----------------+
20 rows in set (0.00 sec)

link_id сортирует первичный идентификатор в таблице. Он сообщает мне, какие URL-адреса появляются в ссылке 1, ссылке 2 и т. Д.

Я хочу выполнить следующее: 1. Получите все уникальные URL-адреса, 2. Show which links the URL belongs to

So an example output would be:

+-----------------+---------+
| url             | link_id |
+-----------------+---------+
| www.example.com |       1 |
| www.example.com |       2 |
| www.abc.com     |       1 |
| www.abc.com     |       2 |
| www.test.com    |       1 |
| www.test.com    |       2 |
| www.t1.com      |       1 |
| www.newtest.com |       1 |
| www.testing.com |       1 |
| www.web1.com    |       1 |

...and so on.

So you can see that www.example.com appears twice since it is associated with both links 1 and 2, but web1.com appears only once since it belongs only to link 1.

I have tried several different group by but I only end up scratching my head even more.

Any help is appreciated. Here is the table dump if anyone needs:

CREATE TABLE IF NOT EXISTS `table1` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `link_id` tinyint(3) unsigned DEFAULT NULL,
  `url` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=21 ;

INSERT INTO `table1` (`id`, `link_id`, `url`) VALUES
(1, 1, 'www.example.com'),
(2, 1, 'www.abc.com'),
(3, 1, 'www.test.com'),
(4, 1, 'www.t1.com'),
(5, 1, 'www.newtest.com'),
(6, 1, 'www.testing.com'),
(7, 1, 'www.abc.com'),
(8, 1, 'www.example.com'),
(9, 1, 'www.web1.com'),
(10, 1, 'www.web2.com'),
(11, 2, 'www.dear.com'),
(12, 2, 'www.google.com'),
(13, 2, 'www.flowers.com'),
(14, 2, 'www.yahoo.com'),
(15, 2, 'www.abc.com'),
(16, 2, 'www.dell.com'),
(17, 2, 'www.web.com'),
(18, 2, 'www.example.com'),
(19, 2, 'www.test.com'),
(20, 2, 'www.abc.com');