Question

The way I usually create my applications is by creating the database first and using LINQ to SQL to create the classes for me.
But in my current project I want to try and use inheritance, and I don’t think it’s possible creating inheritance in a database?

Thus I’m wondering how I would create an inheriting class with SQL Server / LINQ, so I can save / get data from my database.
For example if I have
The parent:

- contact (id, name, telephone number, address, email..) 

And the children:

- customer(id, title, activity, discount, vat...)
- supplier (id, title, activity, vat, bankaccount_number, manager, expiration_day...)
- driver (id, first name, hire_date, fire_date, function, date of birth...)

How would I create a working database connection for these classes?
I don’t have a lot of experience with creating classes as I usually let Visual Studio (LINQ) create them for me.

I’d greatly appreciate any help,
Thanks 🙂

Answer 1

Linq-to-Entities (Entity Framework) provides this functionality out of the box.

You can design your entities as being derivations of a parent class, and then create queries for them like so:

var customers = context.ContactSet.OfType<Customer>();
var suppliers = context.ContacctSet.OfType<Supplier>();
var drivers = context.ContactSet.OfType<Driver>();

The parent class and children classes share an entity key. The database should have a (1:0 or 1) relationship between the parent table and child tables.

I don’t think anything similar exists for Linq-to-SQL.