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类图中的重复度与ER图中实体的基数有什么异同？
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类图中的重复度与ER图中实体的基数有什么异同？
时间：2022-01-11 08:06
关键词：
CMS专题
计算机软件水平考试
中级数据库系统工程师
数据库设计
答案解析
重复度类似于ER模型中实体基数的概念，但是这是两个相反的概念。实体基数是指与一个实体有联系的另一端实体数目的最小、最大值，基数应写在这一端实体的边上；而重复度是指参与关联的这一端对象数目的最小、最大值，重复度应写在这一端类的边上。
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