For the ERD, you will be expected to deliver a logical ER model drawn in crow’s foot notation that satisfies the case specification of the assignment. No other notation is allowed. The ERD should be filled with appropriately defined entity sets, attributes, primary keys, foreign keys, relationships with cardinalities, and verb phrases.
Case:
Background
Piazza1 is created with one goal: to enable students learning from each other collaboratively in a shared virtual space through questions and answers even they are physically separated or being too shy to engage in face-to-face
It offers a web service2 that combines a forum with a wiki which means the contents are version controlled and editable among participants 1:https://piazza.com/about/story 2:https://en.wikipedia.org/wiki/Piazza_web_service
Account
To join Piazza for the first time signing up an account is required. An account consists of account ID first name last name preferred email password and avatar. It may associate with more emails for receiving notification
After an account is created it may be enrolled to a class as either student or instructor but not both. However an account could have an instructor role in a class and a student role in another class
As part of the enrolment an account specifies their preference of notification for new post and updated post. The options for preference is standardised e.g. real time daily digest smart digest and no emails. There is an additional option to automatically follow every post in a class
Class
A class is composed of class ID class number name estimated size start date status and url. The class ID is used as unique identifier whereas the class number and name are common references used in the school.
When a class is created it must be associated with a school (e.g. The University of XxX) and a term (e.g. Semester 1 2019). A term is named specifically to follow a school’s convention and a school must register with one domain or more e.g. xxxuni.ac.nz
The instructor who creates a class is always the first account enrolled and a list of folders e.g. lecture lab general etc is defined to manage posts.
Post
While a post associates with a class ID and a post number a post ID is used as the unique identifier for each post among all classes. It has post type post date summary detail and whether it is pinned. Each post must be tagged with one or more folders
There are two post types: note or question. A note is a post that requires no answer whereas a question expects answers. Each question associates at most with one student’s answer and one instructor’s answer
A post may have follow-ups and a follow-up may have comments. Whether it is an answer a follow-up or a comment essentially they all have a detail attribute to store the content. A follow-up has an additional attribute to indicate if it has been resolved
Version
When a writing i.e. post answer follow-up or comment is composed a version is created. A writing must associate with one version or more
In Piazza the latest version of a writing would be displayed by default but all versions are accessible for tracking the development of the writing
Each version of a writing is composed by one and only one account and the composer could choose if their identity is revealed or anonymised
Read
When a post is viewed by an account the first time which may include answers follow-ups and comments a read is created with a read date. Any further views or actions from the reader would update the read date
A reader may endorse a post and / or the associated answers if it is a question. Furthermore a reader may follow a post to receive update notification. A reader may star a post as one of their favorites
The actions of endorsement following and starring could be undone and / or redone if a reader chooses to do so
Login Bonus
Piazza could tell the total number of enrolled accounts in a class that are currently logged on and the total number of enrolled accounts in a class that have logged on in the last seven days
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