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经过多次传递后，我想知道是否可以进一步优化此查询？非常感谢任何见解。除了必须使用一堆不理想的子查询之外，我还必须使用其中一个两次，因为“标签”引用不能在 where 子句中使用......（无法弄清楚如何将此重写为连接以解决该问题）

SELECT `t1`.*, 
(SELECT GROUP_CONCAT(tag_id) FROM media_tag WHERE media_id=t1.id GROUP BY media_id ) as tags, 
(SELECT GROUP_CONCAT(award_id) FROM media_award WHERE media_id=t1.id GROUP BY media_id ) as awards, 
(SELECT GROUP_CONCAT(client_id) FROM media_client WHERE media_id=t1.id GROUP BY media_id ) as clients, 
(SELECT GROUP_CONCAT(collaborator_id) FROM media_collaborator t2 LEFT JOIN collaborator t3 ON t2.collaborator_id=t3.id WHERE media_id=t1.id AND t3.collaborator_type_id='1' GROUP BY media_id ) as agencies, 
(SELECT GROUP_CONCAT(collaborator_id) FROM media_collaborator t2 LEFT JOIN collaborator t3 ON t2.collaborator_id=t3.id WHERE media_id=t1.id AND t3.collaborator_type_id<>'1' GROUP BY media_id ) as collaborators, 
`t2`.`idx`, `t2`.`type` 
FROM (`media` t1) 
LEFT JOIN `sort` t2 ON `t1`.`id`=`t2`.`id` AND t2.type="media" 
WHERE 
    FIND_IN_SET('1',(SELECT GROUP_CONCAT(tag_id) FROM media_tag WHERE media_id=t1.id GROUP BY media_id )) 
    AND IF(t2.tag_id IS NOT NULL,t2.tag_id='1',1) 
GROUP BY `t1`.`id` 
ORDER BY `t1`.`date_mod` DESC, `title` ASC, `t2`.`idx` ASC, `date_mod` DESC, `title` ASC
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你应该尽量减少每一行的选择语句，你可以加入那些行并按一些标识符分组，如果你可以发布你的表结构并告诉我们你想从他们那里得到什么信息会更好......

于 2012-12-18T21:53:05.197 回答