Question

数据库ER图SQL语言作业，高分求助，英文题

Project 1
Project Specification
We want to create a database for a telecommunication company that provides Broadband (BB) and Home Telephone (HT) services offered through service plans. For each service plan, we need to keep the plan code, name, service type (BB or HT), description (detailed information about the service), contract period and monthly fee.
The followings are some examples of the service plans. BB stands for Broadband and HT for Home
Telephone.（见图片）
For each customer, we create a record with his/her person id, full name, contact phone number, billing address, payment method.
A customer subscribes to at least a service plan.
A subscription has a subscription ID, activation date and installation address and belongs to a single customer.
Each subscription is either a BB plan or HT plan subscription, but not both. A BB plan subscription has additional email and password attributes. A HT plan subscription has additional phone number attribute.
Every customer must select one payment method for all his subscriptions - cash or auto-pay using credit card. If the customer uses auto-pay, his/her credit card information (i.e., card number, owner
name, expiry date) must be stored.
Tasks
1. You need to create an ER diagram for the above description. Please make your own reasonable assumptions (if any) and state them clearly.
2. Convert your ER diagram to tables.（using SQL statement）

Answer 1

对，明天早上第一节课交是吧，有一个思路，建立3元关系，把 customer , subscription,和service plan，这样在把属性加上，特殊的地方就是service type和payment method，可以考虑不把他们写成属性，而是写成实体，这样可以用继承的关机，把BB和HT，crash和auto_pay都设置成具体继承实体，这样可否？挺麻烦的。都是一家人，分当然给我，多谢哈，哥们儿！

Answer 2

明天交作业了，都没准呢。分给我吧...

Answer 3

求分...