[MySQL] Problem z nadaniem indeksów w mysql Opcje

[dma3]

Próbując nałożyć tworzenie indeksów w MySQL

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ALTER TABLE 'forum_' ADD INDEX ('id_');
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dostaje blad:

#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 ''forum_' ADD INDEX (id_)' at line 1

Struktuta tabeli forum_

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CREATE TABLE `forum_` (
  `id` int(8) NOT NULL AUTO_INCREMENT,
  `id_` int(8) NOT NULL DEFAULT '0',
  `id_b` int(8) NOT NULL DEFAULT '0',
  `status` int(8) NOT NULL DEFAULT '0',
  `zablokowany` int(8) NOT NULL DEFAULT '0',
  `autor` varchar(255) collate utf8_swedish_ci NOT NULL DEFAULT '',
  `temat` text collate utf8_swedish_ci NOT NULL,
  `opis` text collate utf8_swedish_ci NOT NULL,
  `tresc` text collate utf8_swedish_ci NOT NULL,
  `odslony` int(8) NOT NULL DEFAULT '0',
  `nowy_temat` int(8) NOT NULL DEFAULT '0',
  `ostatni_post` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
  `ikona` int(255) NOT NULL DEFAULT '0',
  `data_dodania` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
  `data_edycji` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
  `ip_autora` varchar(30) collate utf8_swedish_ci NOT NULL DEFAULT '',
  `html` int(8) NOT NULL DEFAULT '0',
  `xcode` int(8) NOT NULL DEFAULT '0',
  `emoikony` int(8) NOT NULL DEFAULT '0',
  `ip` varchar(50) collate utf8_swedish_ci NOT NULL DEFAULT '',
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=20655 DEFAULT CHARSET=utf8 COLLATE=utf8_swedish_ci AUTO_INCREMENT=20655 ;
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co robie zle ?

w bazie juz sa rekordy.


a jak daje

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ALTER TABLE `forum_c` ADD INDEX `in` ( `id_` ( 8 ) )
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dostaje

#1089 - Incorrect sub part key; the used key part isn't a string, the used length is longer than the key part, or the storage engine doesn't support unique sub keys