Introduction
Database design最简单的设计模型就是E-R模型,E-R建模工具有很多,最简单方便的当属Microsoft Office Visio。
E-R模型图由实体Entities以及关系Relationship组成,其中实体Entities可能包含属性Properties/Attributes。E-R图反映了现实世界中的一些现象,如客户和书店、供销商和书店之间是供求关系,而客户、书店和供销商之间,各自又存在属性,如名称、电话等。
关系不一定是一对一,也可能是一对多、多对一、多对多关系,如一本书可以对应多个作者,而一名作者也可以对应多本书。这类情形也可以由E-R图反映。
Requirement
In this assignment, you are designing an online bookstore database. The storekeeper wants to record the publishers, books and buyer. For each publisher, the storekeeper records the email address, phone number and book genres. For each book the storekeeper records the ISBN, book title, authors and price. For each buyer the storekeeper records the name, phone number, and purchase amount in total.
Note that the storekeeper doesn’t want to record which book is bought by which buyer. You should to drow an E-R diagrams to demonstrate your database design.