Databases Reference
In-Depth Information
FIGURE 2.6
Adding database objects to the model.
The Update Wizard is very similar to the Entity Data Model Wizard you used to create the
model initially. It uses the connection string stored in the application configuration file to
retrieve the list of database tables, views, and stored procedures that exist in the target
database but have not been added to the entity model yet. Any tables that were previously
included in the model are refreshed automatically, meaning that database schema changes
are merged in the model. For this example, add the Suppliers table and click the Finish
button.
NOTE
Note that the Update Wizard uses the pluralization and foreign key column options you
selected when creating the model. Avoid changing these options; it results in inconsis-
tently named entity classes and object set properties.
When the Update Wizard finishes updating the model, you see the new entity types,
Supplier in this case, displayed in the Entity Designer along with the association (shown
as a dotted line) that was created based on the
SupplierID
foreign key, similar to what is
shown in Figure 2.7.
The Entity Framework supports several different types of associations. What we have in
this case is a one-to-many association between Supplier and Product entities. In other
words, for each
Supplier
instance there might be zero or more
Product
instances as indi-
cated by the
*
symbol on the design surface. The
SupplierID
property is nullable, so a
Product does not have to have a Supplier specified, which is indicated by the 0..1 multi-
plicity in the model. If the SupplierID column did not allow null values, making a
