[英]Mysql LEFT OUTER JOIN with LIMIT?
這是我的查詢
SELECT `t`.`id` AS `t0_c0`
, `news`.`id` AS `t2_c0`
, `news`.`title` AS `t2_c1`
, `news`.`url` AS `t2_c2`
, `news`.`date` AS `t2_c3`
, `news`.`hash` AS `t2_c4`
, `news`.`list_id` AS `t2_c5`
FROM
`words` `t`
LEFT OUTER JOIN `words_news` `news_news`
ON (`t`.`id` = `news_news`.`word_id`)
LEFT OUTER JOIN `news` `news`
ON (`news`.`id` = `news_news`.`news_id`)
WHERE
(`t`.`id` IN (8229, 8574, 7901))
並且我只需要從news
表中選擇5條新聞,但是不知道如何,該如何編寫查詢?
嘗試這個:
SELECT `t`.`id` AS `t0_c0`
, `news`.`id` AS `t2_c0`
, `news`.`title` AS `t2_c1`
, `news`.`url` AS `t2_c2`
, `news`.`date` AS `t2_c3`
, `news`.`hash` AS `t2_c4`
, `news`.`list_id` AS `t2_c5`
FROM
`words` `t`
LEFT OUTER JOIN `words_news` `news_news`
ON (`t`.`id` = `news_news`.`word_id`)
LEFT OUTER JOIN (SELECT * FROM `news` LIMIT 5) `news`
ON (`news`.`id` = `news_news`.`news_id`)
WHERE
(`t`.`id` IN (8229, 8574, 7901));
要么
SELECT `t`.`id` AS `t0_c0`
, `news`.`id` AS `t2_c0`
, `news`.`title` AS `t2_c1`
, `news`.`url` AS `t2_c2`
, `news`.`date` AS `t2_c3`
, `news`.`hash` AS `t2_c4`
, `news`.`list_id` AS `t2_c5`
FROM
`words` `t`
LEFT OUTER JOIN `words_news` `news_news`
ON (`t`.`id` = `news_news`.`word_id`)
LEFT OUTER JOIN `news` `news`
ON (`news`.`id` = `news_news`.`news_id`)
JOIN (SELECT @var_ctr := 0) a
WHERE IF(`news`.`id` IS NOT NULL, @var_ctr := @var_ctr + 1, @var_ctr) <= 5
AND (`t`.`id` IN (8229, 8574, 7901));
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