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我有一个冗长的 MySQL 查询，我正在尝试使用 FULL OUTER JOIN，它在 MySQL 中不存在：

select c.cat_id,c.cat_name as cat_name, 
 c.cat_desc, c.cat_image, mi.filename, 
 l.link_id, l.user_id, l.address,l.city, 
 l.country,l.link_created,l.link_desc, 
 l.email,l.fax,l.link_hits, l.link_modified,
 l.link_name,l.postcode, l.price,l.link_rating, 
 l.state,l.telephone,l.link_votes,
 l.website, l.link_id, l.link_visited, cf.value
from j25_mt_cats as c,
j25_mt_links as l 
LEFT JOIN j25_mt_cfvalues AS cf ON (cf.link_id = l.link_id),
j25_mt_images AS mi,
j25_mt_cl as cl
where cf.cf_id = 40 and cl.link_id = l.link_id 
 AND mi.link_id = l.link_id AND mi.ordering < 2  
 AND c.cat_id = cl.cat_id and c.cat_published = 1 
 AND c.cat_approved = 1 and l.link_published = 1 and l.link_approved = 1
ORDER BY RAND() DESC;

上面的 LEFT JOIN 是我希望使用 FULL OUTER JOIN 逻辑的地方。我知道它必须在 UNION 中使用多个 JOIN，但我的尝试导致了各种语法错误。

将上述内容更改为 FULL OUTER JOIN 逻辑的正确语法是什么？

我正在尝试这个：

select c.cat_id,c.cat_name as cat_name, 
 c.cat_desc, c.cat_image, mi.filename, 
 l.link_id, l.user_id, l.address,l.city, 
 l.country,l.link_created,l.link_desc, 
 l.email,l.fax,l.link_hits, l.link_modified,
 l.link_name,l.postcode, l.price,l.link_rating, 
 l.state,l.telephone,l.link_votes,
 l.website, l.link_id, l.link_visited, cf.value
from j25_mt_cats as c,
j25_mt_links as l 
LEFT OUTER JOIN j25_mt_cfvalues AS cf ON (cf.link_id = l.link_id),
j25_mt_images AS mi,
j25_mt_cl as cl
UNION ALL
select c.cat_id,c.cat_name as cat_name, 
 c.cat_desc, c.cat_image, mi.filename, 
 l.link_id, l.user_id, l.address,l.city, 
 l.country,l.link_created,l.link_desc, 
 l.email,l.fax,l.link_hits, l.link_modified,
 l.link_name,l.postcode, l.price,l.link_rating, 
 l.state,l.telephone,l.link_votes,
 l.website, l.link_id, l.link_visited, cf.value
FROM j25_mt_cats as c,
j25_mt_links as l
RIGHT OUTER JOIN j25_mt_cfvalues AS cf ON cf.link_id = l.link_id,
j25_mt_images AS mi,
j25_mt_cl as cl
where cf.cf_id = 40 and cl.link_id = l.link_id 
 AND mi.link_id = l.link_id AND mi.ordering < 2  
 AND c.cat_id = cl.cat_id and c.cat_published = 1 
 AND c.cat_approved = 1 and l.link_published = 1 and l.link_approved = 1
 AND cf.link_id IS NULL
ORDER BY RAND() DESC;

但是它需要几分钟才能运行，然后#126 - Incorrect key file for table '/tmp/#sql_4f82_0.MYI'; try to repair it 当我认为我更接近正确的语法时返回。磁盘未满，甚至未关闭。这也不是一个表，它只是我在 phpMyAdmin 中运行的一个查询。

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2 回答 2

1

当您填充临时目录时，通常会出现此问题，并且在您的情况下，您的查询可能会创建一个巨大的临时文件。

除了优化您的查询外，请尝试在查询期间监视临时目录所在的分区 show variables like 'tmpdir';。

于 2013-09-24T08:13:12.467 回答
1

如果可能，请提供表格设计，示例列，我猜未知列的问题是因为您的底部连接缺少一些演员表

select c.cat_id,c.cat_name as cat_name, 
c.cat_desc, c.cat_image, mi.filename, 
l.link_id, l.user_id, l.address,l.city, 
l.country,l.link_created,l.link_desc, 
l.email,l.fax,l.link_hits, l.link_modified,
l.link_name,l.postcode, l.price,l.link_rating, 
l.state,l.telephone,l.link_votes,
l.website, l.link_id, l.link_visited, cf.value
from j25_mt_cats as c,
j25_mt_links as l 
LEFT OUTER JOIN j25_mt_cfvalues AS cf ON (cf.link_id = l.link_id)

//you mi is missing here [开始]

j25_mt_images AS mi,
j25_mt_cl as cl
where cf.cf_id = 40 and cl.link_id = l.link_id 
AND mi.link_id = l.link_id AND mi.ordering < 2  
AND c.cat_id = cl.cat_id and c.cat_published = 1 
AND c.cat_approved = 1 and l.link_published = 1 and l.link_approved = 1
AND cf.link_id IS NULL

// 结尾

UNION ALL
select c.cat_id,c.cat_name as cat_name, 
c.cat_desc, c.cat_image, mi.filename, 
l.link_id, l.user_id, l.address,l.city, 
l.country,l.link_created,l.link_desc, 
l.email,l.fax,l.link_hits, l.link_modified,
l.link_name,l.postcode, l.price,l.link_rating, 
l.state,l.telephone,l.link_votes,
l.website, l.link_id, l.link_visited, cf.value

//你忘了在这里定义 c,l,cf

FROM j25_mt_cats as c, j25_mt_links as l 
RIGHT OUTER JOIN j25_mt_cfvalues as cf ON cf.link_id = l.link_id,
j25_mt_images AS mi,
j25_mt_cl as cl
where cf.cf_id = 40 and cl.link_id = l.link_id 
AND mi.link_id = l.link_id AND mi.ordering < 2  
AND c.cat_id = cl.cat_id and c.cat_published = 1 
AND c.cat_approved = 1 and l.link_published = 1 and l.link_approved = 1
AND cf.link_id IS NULL
ORDER BY RAND() DESC;
于 2013-09-23T03:39:01.140 回答