Entity Set

Since each user can have zero, one, or several projects and a group project can have several participating users, we model the relation between them as many-to-many.

In each project, there could be many tasks which participants would complete to advance the progress of the project. There should be thus a one-to-many relation between Project and Task, and between user and task.

For each task, we designed a comment thread, in which students can discuss their problems, or ask their supervisors for help, to resolve them faster. Since there can be many comments in a task, the relation between Task and Comment should be one-to-many.

There can be comments replying to other comments, constructing a tree data structure. This structure is described by a self-referential one-to-many relation.

Additionally, there should be a Artifact entity for storing reports and slides. Each project can have one report and one slide.

We allowed uploading multiple revisions of reports and slides, considering that the group can continually update their reports and presentations. Each Artifact entity thus can have multiple associated File as revisions.

However, a file does not necessarily tie to any project, since they can be referred in comments or by academic assistants in their statistical reports.

Visually, the relations between entities described above can be represented in Figure 29.

Figure 29 Relationship between entities in the database

In each entity, there are other attributes and metadata which assists the management. They are described in the following sections.

• User
• Project
• Task
• Artifact
• Comment
• File