当前位置:首页计算机类软件水平考试中级数据库系统工程师->某学生想要设计一个博客系统,在数据库的概念设计阶段提出了如下

某学生想要设计一个博客系统,在数据库的概念设计阶段提出了如下图所示的E-R模型,其中的联系类型为三元联系,联系的属性为( 64 )。

中级数据库系统工程师,历年真题,2022年上半年(上午)《数据库系统工程师》真题

  • A.发表
  • B.发表时间
  • C.用户
  • D.无
答案: B
本题解析:

E-R模型3要素:实体、联系和属性。实体用矩形框表示,在框中记入实体名;联系用菱形框表示,在框中记入联系名;属性用椭圆形表示,将属性名记入框中。

另外还有连线,用在实体与属性之间;实体与联系之间;联系与属性之间用直线相连,并在直线上标注联系的类型。(对于一对一联系,要在两个实体连线方向各写1;对于一对多联系,要在一的一方写1,多的一方写*;对于多对多关系,则要在两个实体连线方向各写*,*。)

更新时间:2023-06-07 16:06
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