EER Diagram - Mixing Specialization and Disjointness Constraints Among Subtypes
I'm trying to design an EER diagram that has the supertype Student with the following subtypes: Undergraduate, Graduate, and Research Assistant. A Student must be either an Undergraduate or a Graduate, and a Student may or may not be a Research Assistant.
I'm not entirely sure how to depict these relationships. Should I have supertype/subtype relationships going from Student to subtypes Undergraduate and Graduate with total specialization and disjointness while a separate relationship goes to Research Assistant with only partial specialization?
Or should I have relationships that have total specialization and overlapping and define the subtype discriminator to reflect the constraints above?
Sorry if I'm missing something obvious.
Your first diagram is correct and clearly depicts the specialization you described.
- Is better use an empty value as a '' or as NULL?
- Max length for client ip address
- Can a database support "Atomicity" but not "Consistency" or vice-versa?
- How to link 3 tables where 2 of them are many-to-many?
- how to model discount on items in a database?
- specific queries for car park database design
- Database design for school fee processing
- User role permissions for different modules using bitwise operators
- Best Practice for Designing User Roles and Permission System?
- Entity storing it's status as a FK to a status table. Can I update the FK once the status changes?
- Which is the parent and which the child in a SQL relationship?
- How should the device store save the groupId if you have a new device and an account?
- Use redis list or custom list?
- Database schema of messaging application
- Database design: Aggregate vs Store
- Improve database design for online exam
- Database design: Calculating the Account Balance
- Derived account balance vs stored account balance for a simple bank account?
- DB Design: how to indicate if a column data is public or private
- DynamoDB Index Design for Finding Items Where an Attribute Contains a Specific Value
- How should international geographical addresses be stored in a relational database?
- database - flattened out vs. normalized
- Ensure uniqueness in join table with start/end dates
- Does a SELECT query always return rows in the same order? Table with clustered index
- Reuse Entity in Entity Framework Core
- How to reduce the required storage space for large indexes and large PostgreSQL tables to improve and ensure performance?
- "Dynamic" tables in SQL?
- How to programmatically check if row is deletable?
- How does PostgreSQL enforce the UNIQUE constraint / what type of index does it use?
- How do I structure data common to all users in Cloud Firestore?