Question

我有一个声明，根据链接表基于共享标签和扬声器的数量对项目进行排名，但我希望它能够从主tbl_talks中提取talk_title和talk_brief信息，而这些信息实际上不在查询中现在（只使用链接表）。基本上，链接表有talk_id和tag_id或talk_id和speaker_id。

我尝试了几种尝试LEFT JOIN的方法，或者在应用了union的配对SELECT中添加tbl_talks但没有运气。我需要将tbl_linking_talk_tag.talk_id和tbl_linking_speakers_talk与tbl_talks.talk_id相关联，然后从tbl_talks获取talk_title和talk_brief

SELECT talk_id, count(*) AS common_term_count FROM 
      (
      SELECT talk_id FROM tbl_linking_talk_tag WHERE tag_id IN 
         (SELECT tag_id FROM tbl_linking_talk_tag WHERE talk_id = 1)
      UNION ALL 
      SELECT talk_id FROM tbl_linking_speakers_talk WHERE speaker_id IN
         (SELECT speaker_id FROM tbl_linking_speakers_talk WHERE talk_id = 1)
       ) AS accumulator_table

 WHERE talk_id != 1 

 GROUP BY talk_id

 ORDER BY common_term_count DESC

Answer 1

在这种情况下，不要认为你需要一个工会。如果你需要的只是数数，那么为什么不试试像......

SELECT talk_id，（SELECT count（*）FROM tbl_linking_talk_tag sub WHERE tag_id IN （SELECT tag_id FROM tbl_linking_talk_tag WHERE talk_id = 1）和maintalk.talk_id = sub.talk_id）+ （SELECT count（*）FROM tbl_linking_speakers_talk sub1 WHERE speaker_id IN （SELECT speaker_id FROM tbl_linking_speakers_talk WHERE talk_id = 1）和maintalk.talk_id = sub1.talk_id ），talk_title，talk_brief 来自maintalk 其中talk_id！= 1 按talk_id分组

语法可能需要一些修复，但方法是

从维护

中选择列

Answer 2

我使用了这段代码：

 SELECT a.talk_id, a.talk_image, a.talk_title, a.talk_brief, count(b.talk_id)  AS common_term_count 
        FROM tbl_talks a LEFT OUTER JOIN
             (
             SELECT talk_id FROM tbl_linking_talk_tag WHERE tag_id IN 
                (SELECT tag_id FROM tbl_linking_talk_tag WHERE talk_id = 1)
             UNION ALL 
             SELECT talk_id FROM tbl_linking_speakers_talk WHERE speaker_id IN
                (SELECT speaker_id FROM tbl_linking_speakers_talk WHERE talk_id = 1) 
             ) AS b
             ON a.talk_id = b.talk_id       
        WHERE a.talk_id != 1        
        GROUP BY b.talk_id      
        ORDER BY common_term_count DESC

如何为这个庞大的SQL联合语句添加联接？

2 个答案: