数据库系统基础教程第四章答案(共45页).doc

SolutionsChapter 4 4.1.1 4.1.2a)b)c)In c we assume that a phone and address can only belong to a single customer (1-m relationship represented by arrow into customer). d)In d we assume that an address can only belong to one customer and a phone can exist at only one address.If the multiplicity of above relationships were m-to-n, the entity set