CREATE TABLE `questions` (
`question_id` int(5) unsigned NOT NULL AUTO_INCREMENT,
`FK_quiz_id` int(5) unsigned NOT NULL,
`question_identify_text` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`question_id`),
KEY `FK_quiz_id` (`FK_quiz_id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
CREATE TABLE `question_multilingual` (
`question_multilingual_id` int(5) unsigned NOT NULL AUTO_INCREMENT,
`FK_question_id` int(5) unsigned NOT NULL,
`FK_language_id` smallint(3) unsigned NOT NULL,
`question` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`question_multilingual_id`),
UNIQUE KEY `FK_question_id` (`FK_question_id`,`FK_language_id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
CREATE TABLE `choices` (
`choice_id` int(5) unsigned NOT NULL AUTO_INCREMENT,
`FK_question_id` int(5) unsigned NOT NULL,
`choice_identify_text` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`choice_id`),
KEY `FK_question_id` (`FK_question_id`)
) ENGINE=MyISAM AUTO_INCREMENT=6 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
CREATE TABLE `choice_multilingual` (
`choice_multilingual_id` int(5) unsigned NOT NULL AUTO_INCREMENT,
`FK_choice_id` int(5) unsigned NOT NULL,
`FK_language_id` smallint(3) unsigned NOT NULL,
`choice` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`choice_multilingual_id`),
UNIQUE KEY `FK_choice_id` (`FK_choice_id`,`FK_language_id`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
这些是表结构。
EXPLAIN SELECT * FROM `questions` inner join question_multilingual on question_multilingual.FK_question_id = questions.question_id AND question_multilingual.FK_language_id = 1 INNER JOIN choices ON choices.FK_question_id = questions.question_id INNER JOIN choice_multilingual ON choice_multilingual.FK_choice_id = choices.choice_id AND choice_multilingual.FK_language_id = 1 WHERE FK_quiz_id = 1
1 SIMPLE choice_multilingual NULL ALL FK_choice_id NULL NULL NULL 14 10.00 Using where
1 SIMPLE question_multilingual NULL ref FK_question_id,FK_language_id FK_language_id 2 const 2 100.00 NULL
1 SIMPLE choices NULL eq_ref PRIMARY,FK_question_id PRIMARY 4 quizzes.choice_multilingual.FK_choice_id 1 14.29 Using where
1 SIMPLE questions NULL eq_ref PRIMARY,FK_quiz_id PRIMARY 4 quizzes.question_multilingual.FK_question_id 1 100.00 Using where
我尝试更改复合索引，单个索引。试图添加列。 结果各不相同，但无论如何都没有得到优化的结果。