niyue

标识关系与非标识关系的区别

In programming on August 29, 2006 at 11:54 AM

最近在用Rose画数据库的数据模型设计图,画出来的不是ER图,但是和ER图比较相近。不过里面有两个概念一直没搞懂,identifying/non-identifying relationship,仔细查了一下,有不少介绍这个知识的文章。

从结果来看的话,identifying关系中的子表必须将父表的外键作为主键,而non-identifying则不必。

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