手动实体框架关联

Question

I have the following tables:

Table Group (
   id INT PK,
   year INT PK,
   name VARCHAR
)

Table Person (
    id PK,
    GroupID INT,
    name VARCHAR
)

The database does not have foreign keys defined so I want to create a manual association from the Person tables GroupID to the Group tables id .

To do this I right click Person and Add an association. I create a Many to One association and everything works. The problem is when I go to add the mapping. Because the Group table has two primary keys entity framework was something from the Person table to map to the year key.

What do I need to do to create the association?

Answer 1

You cannot create such association because EF follows same rules as database. All PK columns from principal entity must exists as FK columns in dependent entity.

The only way can be some database view selecting distinct Groups with Id and Name and mapped as read only entity and build navigation between those two. I didn't try it but I guess it should work. It will have its own disadvantages because you will have two completely unrelated entities for group and the entity related to person will not accept any modification (without mapping custom SQL commands or stored procedures to insert, updated and delete operations).