[英]Convert MySQL subquery to JOIN query
我正在嘗試從下面的表結構中獲取quotes.quote,authors.author和tags.tag,
CREATE TABLE IF NOT EXISTS `authors` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`author` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`id`)
);
CREATE TABLE IF NOT EXISTS `quotes` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`quote` text COLLATE utf8_unicode_ci NOT NULL,
`author_id` int(10) unsigned NOT NULL,
PRIMARY KEY (`id`),
KEY `quotes_author_id_foreign` (`author_id`),
);
CREATE TABLE IF NOT EXISTS `quote_tags` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`tag_id` int(10) unsigned NOT NULL,
`quote_id` int(10) unsigned NOT NULL,
PRIMARY KEY (`id`)
);
CREATE TABLE IF NOT EXISTS `tags` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`tag` varchar(225) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`id`)
);
ALTER TABLE `quotes`
ADD CONSTRAINT `quotes_author_id_foreign` FOREIGN KEY (`author_id`) REFERENCES `authors` (`id`);
但是這里的問題是,標記表中的每個引號可能有多個條目,我想以逗號分隔的格式檢索它。
到目前為止,這是我嘗試過的
SELECT `quotes`.`id` , `quotes`.`quote` , `authors`.`author` , (
SELECT GROUP_CONCAT( `tag` )
FROM tags
JOIN quote_tags
WHERE quote_tags.tag_id = tags.id
AND quote_tags.quote_id = quotes.id
) as tags
FROM `quotes`
INNER JOIN `authors` ON `authors`.`id` = `quotes`.`author_id`
INNER JOIN `topics`
但是我不想使用子查詢來完成該任務。
請在不使用子查詢的情況下幫助我構建此查詢。
SELECT `_quotes`.`id` , `_quotes`.`quote` , `_authors`.`author`
,GROUP_CONCAT( `tag` )
FROM `_quotes`
INNER JOIN `_authors` ON `_authors`.`id` = `_quotes`.`author_id`
inner join _tags
JOIN _quote_tags
on _quote_tags.tag_id = _tags.id
AND _quote_tags.quote_id = _quotes.id
INNER JOIN `_topics` group by `_quotes`.`id`,`_tags`.`id`
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