For information about the tutorial series, see the first tutorial in the series.
In the previous tutorials, you worked with a simple data model that was composed of three entities.
The same will be true for any view that uses the Student model.
You can also specify data validation rules and validation error messages using attributes.
Notice that several properties are the same in the Student and Instructor entities.
Suppose you want to ensure that users don't enter more than 50 characters for a name.But the Entity Framework can't automatically recognize Instructor ID as the primary key of this entity because its name doesn't follow the ID or classname ID naming convention.Therefore, the attribute if the entity does have its own primary key but you want to name the property something other than classname ID or ID.You can put multiple attributes on one line, so you could also write the There's a one-to-zero-or-one relationship between the Instructor and the Office Assignment entities.
An office assignment only exists in relation to the instructor it's assigned to, and therefore its primary key is also its foreign key to the Instructor entity.
To add this limitation, add attribute but doesn't provide client side validation.