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mysql - DELETE FROM x LEFT JOIN y WHERE xa IS NOT NULL IN table y

问题描述

如何从表 A 中删除表 B 中不存在的记录？

我试过这个：

DELETE FROM
    x
LEFT JOIN
    y
ON
    x.image_hash IS NOT NULL IN y

标签： mysql

解决方案

适当地使用EXISTSorNOT EXISTS子句。

DELETE FROM x WHERE <NOT> EXISTS (SELECT 1 FROM y WHERE y.<something> = x.<some_column> AND <some more conditions>

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