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为什么说二级索引不唯一,不唯一是指什么不唯一呢?

为什么说二级索引不唯一,不唯一是指什么不唯一?


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MySQL 中每个表都有一个聚簇索引, 除此之外的表上的每个非聚簇索引都是二级索引,『不唯一』可能是指聚簇索引只有一个,而二级索引可以有多个。


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