E-R图提供了表示数据库表的实体类型、属性和联系的方法，是表示概念关系模型的一种方式。为表述实体联系模式图形式的数据表模型提供了图形符号。这种数据表模型典型的用在基于数据库的信息系统设计的需求分析阶段，用来描述信息需求和/或要存储在数据库中的表信息的类型。
扩展资料：
E-R图设计的正确与否取决于数据库设计人员能否真正把握表的各个客观对象和他们之间发生的活动，这需要作准确深入的用户需求分析。这些表对象如果需要记录的话，就抽象为E-R图中的实体。
描述实体的众多相关数据就抽象为实体的属性，将具有相同属性的众多实体抽象为实体型。它们之间发生的活动如果也需要记录的话，就抽象为E-R图中的联系，这是E-R图设计的重点。
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第1个回答 推荐于2017-11-24
ER图是基于ER模型（实体关系模型）画的，属于概念模型，是对现实世界的实体及其之间关系的抽象。
数据库表是属于数据模型，用来描述数据的结构关系。
通常我们数据库的设计要经过下面这个过程：
现实世界-〉概念模型-〉数据模型
一般项目的设计中，首先通过需求分析的人员根据客户抽象出 ER图，然后由数据库的设计人员根据ER图和用户对查询等方面的需求设计出数据库的表结构，以及相关的视图和索引。本回答被提问者采纳
数据库表是属于数据模型，用来描述数据的结构关系。
通常我们数据库的设计要经过下面这个过程：
现实世界-〉概念模型-〉数据模型
一般项目的设计中，首先通过需求分析的人员根据客户抽象出 ER图，然后由数据库的设计人员根据ER图和用户对查询等方面的需求设计出数据库的表结构，以及相关的视图和索引。本回答被提问者采纳
第2个回答 2011-06-04
ER图是通过分析问题用一定的方法画出的类似于工作流程的图，但图中主要是流程中的实体（如：班级，教师，学生等）。然后你根据这些主体建立表 基本上就是一个实体一张表（这个具体看下书就会了）。所有的表组成数据库。
第3个回答 2011-06-02
画ER图就是在设计数据库。
ER图就是实体关系图（数据库关系图），主要完成了对系统中数据部分设计。
ER图就是实体关系图（数据库关系图），主要完成了对系统中数据部分设计。
第4个回答 2011-06-11
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female genital because of their special physiological structure , are particularly vulnerable to bacterial invasion, menstrual cycles ,MBT Fora, Work stress, sexual and inappropriate hygiene ,thomas sabo reduziert, vaginal health may change in the weak acid environment to stimulate and gynecological inflammation. Chinese married women suffer from varying degrees of gynecological diseases ,thomas sabo Ringe, the incidence of cervical cancer in developed countries 6 times. Gynecological diseases have become a major threat to women's health killer. Attention to physical health, to develop good health care habits is the key to the prevention of gynecological diseases .
Journal of Preventive Medicine Branch of maternal and child health management expert , said: personal care products are divided into therapeutic and care , treatment and type of personal care products contain ingredients bactericidal drug is only suitable for use in gynecological inflammation phase Not suitable for everyday use when cleaning nursing . If long-term use therapeutic personal care products will hurt the vaginal lactobacilli , vaginal self-purification function of damage , but vulnerable to bacteria . Meanwhile, the strong bactericidal ingredients will harm the delicate genital skin and mucosal tissue,mbt schuhe bestellen, causing vaginal dryness and premature aging.
Topics related articles：
mont blanc rollerball pen S.H.E devil Slimming Treatment Rai
true religion How Breast diet
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