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?
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?
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
另一种选择是使用NOT EXISTS,但通过使用适当的指数可以取得最大的业绩改进。
如果尚未到场,你可能会试图增加。
tapeGenres.tape_id
tapes (tape_id, title)
<>SQL 声明
SELECT tapes.tape_id, tapes.title
FROM tapes t
WHERE NOT EXISTS (SELECT tape_id FROM tapeGenres WHERE tape_id = t.tape_id)
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