首页
登录
从业资格
The entity-relationship (E-R) data model
The entity-relationship (E-R) data model
题库
2022-08-02
30
问题
The entity-relationship (E-R) data model is based on a perception of a real world that consists of a clletion of basic objects, called( ) ,and of relationships among these objects.An entity is a“thing”or "object" in the real world that is distinguishable from other objects.Entities are described in a database by asetof( ) : A relationship isan association among several entities. The set of all entities of the same type and the set of all relationships of the ametype are termed an entity sct and relationship set, respectively. The overall logical structure (schema) of a database can be expressed graphically by an E-R diagram, which is built up from the fllowing components:( ) represent entity set,( ) represent atributes, ete. In addition to entities and relations, the E-R model represents certain(请作答此空)to which thecontents of a database must conform. The entity-relationship model is widely used in database design.A.thingsB.objectsC.conditionsD.constrains
选项
A.things
B.objects
C.conditions
D.constrains
答案
D
解析
转载请注明原文地址:https://tihaiku.com/congyezige/2418662.html
本试题收录于:
中级 数据库系统工程师题库软件水平考试初中高级分类
中级 数据库系统工程师
软件水平考试初中高级
相关试题推荐
Theentity-relationship(E-R)datamodeli
Theentity-relationship(E-R)datamodel
Theentity-relationship(E-R)datamodel
Theentity-relationship(E-R)datamodel
Theentity-relationship(E-R)datamodel
Theentity-relationship(E-R)datamodel
随机试题
Manystudentsfindtheexperienceofattendinguniversitylecturestobeac
[img]2012q1/ct_etoefm_etoeflistz_0822_20121[/img][br]Whydoesthemangotose
道路路基的各种病害或变形的产生,都与地表水和地下水的()和冲刷等破坏作用有关。A
卡伯特环现认为可能是()A.核残余物B.脂蛋白变性C.色素沉着D.血红蛋白聚集
不属于抗假单胞菌青霉素的是A.哌拉西林B.替卡西林C.阿帕西林D.磺苄西林E.阿
2009年主要农业产品产量增长百分比最多与最少的相差多少: A18个百分点
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
县林业和草原局与本局王某等5名干部家属签订了承包该局所管辖的某乡林业检查站的合同
发芽法要求发芽率在A.65%以上 B.70%以上 C.75%以上 D.85
A.亚铁螯合酶 B.ALA合酶 C.红细胞生成素 D.磷酸吡哆醛 E.A
最新回复
(
0
)