Jest 4 w nocy i się już poddaję :D

Nie mam pojęcia, czy tytuł jest adekwatny.

Mam następujące dane:

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user
+---------+-----------+
| user_id | user_name |
+---------+-----------+
|       1 |    Kacper |
|       2 |    Bartek |
|       3 |     Kamil |
|       4 |    Bartek |
+---------+-----------+
 
GROUP
+----------+-------------+
| group_id | group_title |
+----------+-------------+
|        1 |         PHP |
|        2 |         C++ |
|        3 |      Pascal |
+----------+-------------+
 
group_member
+-----------------+-------------------+--------------------+
| group_member_id | group_member_user | group_member_group |
+-----------------+-------------------+--------------------+
|               1 |                 1 |                  1 |
|               2 |                 1 |                  2 |
|               3 |                 2 |                  2 |
|               4 |                 2 |                  3 |
|               5 |                 3 |                  3 |
|               6 |                 3 |                  1 |
|               7 |                 4 |                  2 |
+-----------------+-------------------+--------------------+
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powiedzmy, że to baza danych szkolnego kółka informatycznego, które jest podzielone na 'sekcje'

Chodzi o to, by wyświetlić każdemu użytkownikowi z kim chodzi na konkretne zajęcia tematyczne w postaci:

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dla kacpra(id1)
+--------------------+-----------+
| group_member_group | user_name |
+--------------------+-----------+
|                  1 |    Kacper |
|                  1 |     Kamil |
|                  2 |    Kacper |
|                  2 |    Bartek |
|                  2 |    Eliasz |
+--------------------+-----------+
 
dla bartka(id2)
+--------------------+-----------+
| group_member_group | user_name |
+--------------------+-----------+
|                  2 |    Kacper |
|                  2 |    Bartek |
|                  2 |    Eliasz |
|                  3 |    Bartek |
|                  3 |     Kamil |
+--------------------+-----------+
 
dla kamila(id3)
+--------------------+-----------+
| group_member_group | user_name |
+--------------------+-----------+
|                  3 |    Bartek |
|                  3 |     Kamil |
|                  1 |    Kacper |
|                  1 |     Kamil |
+--------------------+-----------+
 
dla eliasza(id4)
+--------------------+-----------+
| group_member_group | user_name |
+--------------------+-----------+
|                  3 |    Kacper |
|                  3 |    Bartek |
|                  3 |    Eliasz |
+--------------------+-----------+
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Czy ktoś się podejmie i poratuje ? :3

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SELECT group_member_group, user_name FROM `group` g JOIN `group_member` gm ON `gm`.`group_member_user`=`g`.`user_id` WHERE `group_member_group` IN (SELECT `group_member_group` WHERE `group_member_user`=1 /*dla Kacpra*/)
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#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE `group_member_user`=1 /*dla Kacpra*/) LIMIT 0, 30' at line 1
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Jeśli zapytanie będzie wyglądać następująco:

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SELECT group_member_group, user_name FROM `group` g JOIN `group_member` gm ON `gm`.`group_member_user`=`g`.`user_id` WHERE `group_member_group` IN (SELECT `group_member_group` FROM `group_member` WHERE `group_member_user`=1 /*dla Kacpra*/)
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Otrzymuję błąd:

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#1054 - Unknown column 'user_name' in 'field list'
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Nie wiem jak mógłbym coś tu naprawić ;_;

Zrzut bazy:

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--
-- Baza danych: `BAZA`
--
 
-- --------------------------------------------------------
 
--
-- Struktura tabeli dla tabeli `group`
--
 
CREATE TABLE IF NOT EXISTS `group` (
  `group_id` int(11) NOT NULL AUTO_INCREMENT,
  `group_title` varchar(256) NOT NULL,
  PRIMARY KEY (`group_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ;
 
--
-- Zrzut danych tabeli `group`
--
 
INSERT INTO `group` (`group_id`, `group_title`) VALUES
(1, 'PHP'),
(2, 'C++'),
(3, 'Pascal');
 
-- --------------------------------------------------------
 
--
-- Struktura tabeli dla tabeli `group_member`
--
 
CREATE TABLE IF NOT EXISTS `group_member` (
  `group_member_id` int(11) NOT NULL AUTO_INCREMENT,
  `group_member_user` int(11) NOT NULL,
  `group_member_group` int(11) NOT NULL,
  PRIMARY KEY (`group_member_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ;
 
--
-- Zrzut danych tabeli `group_member`
--
 
INSERT INTO `group_member` (`group_member_id`, `group_member_user`, `group_member_group`) VALUES
(1, 1, 1),
(2, 1, 2),
(3, 2, 2),
(4, 2, 3),
(5, 3, 3),
(6, 3, 1),
(7, 4, 2);
 
-- --------------------------------------------------------
 
--
-- Struktura tabeli dla tabeli `user`
--
 
CREATE TABLE IF NOT EXISTS `user` (
  `user_id` int(11) NOT NULL AUTO_INCREMENT,
  `user_name` varchar(256) NOT NULL,
  PRIMARY KEY (`user_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ;
 
--
-- Zrzut danych tabeli `user`
--
 
INSERT INTO `user` (`user_id`, `user_name`) VALUES
(1, 'Kacper'),
(2, 'Bartek'),
(3, 'Kamil'),
(4, 'Bartek');
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[SQL] pobierz, plaintext 
SELECT group_member_group, user_name FROM `group` g JOIN `group_member` gm ON `gm`.`group_member_user`=`g`.`user_id` JOIN `user` u ON u.`user_id`=g.`user_id` WHERE `group_member_group` IN (SELECT `group_member_group` WHERE `group_member_user`=1 /*dla Kacpra*/)
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Chyba da sie pozbyc jednej tabeli, ale teraz nie mam czasu.