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三. 询问、排序和业绩改进
原标题:SQLite query, subquery and performance improvement

具体地说,还有任何其他方式来撰写这一声明:

SELECT tape_id,title 
FROM tapes 
WHERE tape_id NOT IN (SELECT tape_id 
                      FROM tapeGenres)

并改进业绩?

问题回答

考虑使用<代码>LEFT JOIN

SELECT tapes.tape_id, tapes.title
FROM tapes
LEFT JOIN tapeGenres ON tapes.tape_id = tapeGenres.tape_id;
WHERE tapeGenres.tape_id IS NULL




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