Here is my problem. I'm currently working on a database for a person project and I don't figure how to construct my relational model for that :
- A task can be a person task or a project task.
- A task can be a project task affected to a person registered to a project.
- If possible, I don't want to created separated table for the same data (task).
I think I have the same problem but mysql 5.0 doesn't support the CHECK constraint.
I have an "InvoiceLine" that contains a "Product" that can either be of type "A" or "B".
Tables "A" and "B" have a totally different structure.
I guess I also need to create two linking tables, "Product_A" and "Product_B" and create a field ProductType in the "Product" table.
Would the table structure for the two linking tables be the same as with the solution above? Can this work without the CHECK constraint?