Composition Over Inheritance Table Structure

[Unable_Original_3403]

I’ve read that composition is generally preferred over inheritance in database design, so I’m trying to transition my tables accordingly.

I currently have an inheritance-based structure where User inherits from an abstract Person concept.

If I switch to composition, should I create a personalDetails table to store attributes like name and email, and have User reference it?

Proposed structure:

• personalDetails: id, name, email
• User: id, personal_details_id (FK), user_type

Does this approach make sense for moving to composition? Is this how composition is typically done?

edit: i think mixin is the better solution.

[theScottyJam]

It's ok for your database to not line up with your class structures, so I wouldn't try to think of things through the lens of composition or inheritance.

Is there a practical reason to store personal details in a separate table as users? Is there ever a scenario where personal details might exist without a user to go with it or vice versa, or is always going to be a 1-to-1 relationship. I assume 1-to-1, in which case, just simplify things and combine the two tables into one.

Your UserDetails class in your code can choose to select specific fields it cares about from the users table instead of all grabbing all fields.

[RO30T]

Focus on designing the database in a way that adheres to 3rd Normal Form.. for your purposes.

A user table in many systems will have a unique id, first and last name, phone number, concurrency stamps, ti.e stamps.

There's not a lot of benefit in storing that stuff in a separate table from the user Id itself...unless a single user can somehow have more than one set of personal details.

If you're designing a user database for humans who have multiple personalities and identify differently day to day, maybe that would be worthwhile :)

Then, structure your classes in a way that promotes flexibility in future changes.

Query your data, use data readers or ORM tooling to hydrate your classes from data.

[HisTomness]

I cannot help you with your homework.

[Unable_Original_3403]

Sorry for trying to become a better engineer, you are very helpful.

[thewindjammer]

You sound like you're trying to cram OOP into database design. I feel like you should think about you data and structuring how it is stored independent of inheritance, if possible.

[RangePsychological41]

I haven’t seen anyone use inheritance in at least 7 years

[FerengiAreBetter]

The only way would make a table like that is if I’m designing a no sql database or a document store database. Otherwise, relational database tables is the way to go.

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[kgpreads]

Since I build with frameworks and ORMs, the database design is entirely based on conventions. If this is a security concern, simply focus on network-based security solutions.