问题
in a C# project, using EF Database first I've added a foreign key to a table using SQL server management studio.
After that, back to Visual Studio I've updated the model from the database but I couldn't see the "link" (i.e. the line joining the two tables in the .edmx diagram) between the two affected tables. So in the dropdown over the child table I saw this option "Entity key" and when I clicked it the "link" appeared. To be honest, I don't know and I can't understand what it does, cause I can check or uncheck it now without losing the, again let's say "link".
Do you know why this behaviour?
Thanks!!
回答1:
EntityKey is the Entity idea of a Primary Key in a (SQL in your case) database. You should set it for any column that is a primary key, and then you can setup your Entity Associations to match your database associations.
Working with Entity Keys.
Setting correct EntityKeys is a must for getting correct results from SQL Server, because EntityKeys are used as an internal caching key.
来源：https://stackoverflow.com/questions/10138074/whats-entity-key-in-edmx-file