I'm using Entity Framework 4.1 database first approach. I've used legacy database. In my edmx file which created entity classes based on tables in the legacy database, there is a one-to-zero-or-one association between some entities.
Although I explored the tables of database and relation between them I didn't find out how one-to-zero-or-one relation have been implemented in database.
For more information I put some screenshots of my database diagram and the property of its relation and correspondent entities in edmx file:
![enter image description here](https://i.stack.imgur.com/kye49.jpg)
See Question&Answers more detail:
os 与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…